Start changing code to busybox style

I am doing it this way because it is easier to change frome tabs
(busybox) to 2 spaces (toybox).
diff --git a/src/data.c b/src/data.c
index 20fabec..3866c93 100644
--- a/src/data.c
+++ b/src/data.c
@@ -26,105 +26,105 @@
 #include <parse.h>
 
 const char bc_vm_header[] =
-  "bc 1.0\n"
-  "bc copyright (c) 2018 Gavin D. Howard and contributors\n"
-  "Report bugs at: https://github.com/gavinhoward/bc\n\n"
-  "This is free software with ABSOLUTELY NO WARRANTY.\n\n";
+	"bc 1.0\n"
+	"bc copyright (c) 2018 Gavin D. Howard and contributors\n"
+	"Report bugs at: https://github.com/gavinhoward/bc\n\n"
+	"This is free software with ABSOLUTELY NO WARRANTY.\n\n";
 
 const char bc_err_fmt[] = "\n%s error: %s\n\n";
 const char bc_err_line[] = ":%d\n\n";
 
 const char *bc_errs[] = {
-  "VM",
-  "Lex",
-  "Parse",
-  "Math",
-  "Runtime",
-  "POSIX",
+	"VM",
+	"Lex",
+	"Parse",
+	"Math",
+	"Runtime",
+	"POSIX",
 };
 
 const uint8_t bc_err_indices[] = {
-  BC_ERR_IDX_VM, BC_ERR_IDX_VM, BC_ERR_IDX_VM, BC_ERR_IDX_VM,
-  BC_ERR_IDX_LEX, BC_ERR_IDX_LEX, BC_ERR_IDX_LEX, BC_ERR_IDX_LEX,
-  BC_ERR_IDX_PARSE, BC_ERR_IDX_PARSE, BC_ERR_IDX_PARSE, BC_ERR_IDX_PARSE,
-  BC_ERR_IDX_PARSE, BC_ERR_IDX_PARSE, BC_ERR_IDX_PARSE, BC_ERR_IDX_PARSE,
-  BC_ERR_IDX_MATH, BC_ERR_IDX_MATH, BC_ERR_IDX_MATH, BC_ERR_IDX_MATH,
-  BC_ERR_IDX_MATH, BC_ERR_IDX_MATH,
-  BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC,
-  BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC,
-  BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC,
-  BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC,
-  BC_ERR_IDX_POSIX, BC_ERR_IDX_POSIX, BC_ERR_IDX_POSIX, BC_ERR_IDX_POSIX,
-  BC_ERR_IDX_POSIX, BC_ERR_IDX_POSIX, BC_ERR_IDX_POSIX, BC_ERR_IDX_POSIX,
-  BC_ERR_IDX_POSIX, BC_ERR_IDX_POSIX, BC_ERR_IDX_POSIX, BC_ERR_IDX_POSIX,
-  BC_ERR_IDX_VEC, BC_ERR_IDX_VEC,
-  BC_ERR_IDX_VM, BC_ERR_IDX_VM, BC_ERR_IDX_VM,
+	BC_ERR_IDX_VM, BC_ERR_IDX_VM, BC_ERR_IDX_VM, BC_ERR_IDX_VM,
+	BC_ERR_IDX_LEX, BC_ERR_IDX_LEX, BC_ERR_IDX_LEX, BC_ERR_IDX_LEX,
+	BC_ERR_IDX_PARSE, BC_ERR_IDX_PARSE, BC_ERR_IDX_PARSE, BC_ERR_IDX_PARSE,
+	BC_ERR_IDX_PARSE, BC_ERR_IDX_PARSE, BC_ERR_IDX_PARSE, BC_ERR_IDX_PARSE,
+	BC_ERR_IDX_MATH, BC_ERR_IDX_MATH, BC_ERR_IDX_MATH, BC_ERR_IDX_MATH,
+	BC_ERR_IDX_MATH, BC_ERR_IDX_MATH,
+	BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC,
+	BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC,
+	BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC,
+	BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC,
+	BC_ERR_IDX_POSIX, BC_ERR_IDX_POSIX, BC_ERR_IDX_POSIX, BC_ERR_IDX_POSIX,
+	BC_ERR_IDX_POSIX, BC_ERR_IDX_POSIX, BC_ERR_IDX_POSIX, BC_ERR_IDX_POSIX,
+	BC_ERR_IDX_POSIX, BC_ERR_IDX_POSIX, BC_ERR_IDX_POSIX, BC_ERR_IDX_POSIX,
+	BC_ERR_IDX_VEC, BC_ERR_IDX_VEC,
+	BC_ERR_IDX_VM, BC_ERR_IDX_VM, BC_ERR_IDX_VM,
 };
 
 const char *bc_err_descs[] = {
 
-  NULL,
-  "memory allocation error",
-  "I/O error",
-  "file is not text:",
+	NULL,
+	"memory allocation error",
+	"I/O error",
+	"file is not text:",
 
-  "bad character",
-  "string end could not be found",
-  "comment end could not be found",
-  "end of file",
+	"bad character",
+	"string end could not be found",
+	"comment end could not be found",
+	"end of file",
 
-  "bad token",
-  "bad expression",
-  "bad print statement",
-  "bad function definition",
-  "bad assignment: left must be scale, ibase, "
-    "obase, last, var, or array element",
-  "no auto variable found",
-  "function parameter or auto var has the same name as another",
-  "block end could not be found",
+	"bad token",
+	"bad expression",
+	"bad print statement",
+	"bad function definition",
+	"bad assignment: left side must be scale, ibase, "
+		"obase, last, var, or array element",
+	"no auto variable found",
+	"function parameter or auto var has the same name as another",
+	"block end could not be found",
 
-  "negative number",
-  "non integer number",
-  "overflow",
-  "divide by zero",
-  "negative square root",
-  "bad number string",
+	"negative number",
+	"non integer number",
+	"overflow",
+	"divide by zero",
+	"negative square root",
+	"bad number string",
 
-  "could not open file:",
-  "mismatched parameters",
-  "undefined function",
-  "file is not executable:",
-  "could not install signal handler",
-  "bad scale; must be [0, BC_SCALE_MAX]",
-  "bad ibase; must be [2, 16]",
-  "bad obase; must be [2, BC_BASE_MAX]",
-  "number too long: must be [1, BC_NUM_MAX]",
-  "name too long: must be [1, BC_NAME_MAX]",
-  "string too long: must be [1, BC_STRING_MAX]",
-  "array too long; must be [1, BC_DIM_MAX]",
-  "bad read() expression",
-  "read() call inside of a read() call",
-  "variable is wrong type",
-  "signal caught",
+	"could not open file:",
+	"mismatched parameters",
+	"undefined function",
+	"file is not executable:",
+	"could not install signal handler",
+	"bad scale; must be [0, BC_SCALE_MAX]",
+	"bad ibase; must be [2, 16]",
+	"bad obase; must be [2, BC_BASE_MAX]",
+	"number too long: must be [1, BC_NUM_MAX]",
+	"name too long: must be [1, BC_NAME_MAX]",
+	"string too long: must be [1, BC_STRING_MAX]",
+	"array too long; must be [1, BC_DIM_MAX]",
+	"bad read() expression",
+	"read() call inside of a read() call",
+	"variable is wrong type",
+	"signal caught",
 
-  "POSIX only allows one character names; the following is bad:",
-  "POSIX does not allow '#' script comments",
-  "POSIX does not allow the following keyword:",
-  "POSIX does not allow a period ('.') as a shortcut for the last result",
-  "POSIX requires parentheses around return expressions",
-  "POSIX does not allow boolean operators; the following is bad:",
-  "POSIX does not allow comparison operators outside if or loops",
-  "POSIX requires exactly one comparison operator per condition",
-  "POSIX does not allow an empty init expression in a for loop",
-  "POSIX does not allow an empty condition expression in a for loop",
-  "POSIX does not allow an empty update expression in a for loop",
-  "POSIX requires the left brace be on the same line as the function header",
+	"POSIX only allows one character names; the following is bad:",
+	"POSIX does not allow '#' script comments",
+	"POSIX does not allow the following keyword:",
+	"POSIX does not allow a period ('.') as a shortcut for the last result",
+	"POSIX requires parentheses around return expressions",
+	"POSIX does not allow boolean operators; the following is bad:",
+	"POSIX does not allow comparison operators outside if or loops",
+	"POSIX requires exactly one comparison operator per condition",
+	"POSIX does not allow an empty init expression in a for loop",
+	"POSIX does not allow an empty condition expression in a for loop",
+	"POSIX does not allow an empty update expression in a for loop",
+	"POSIX requires the left brace be on the same line as the function header",
 
-  "index is out of bounds",
-  "item already exists",
+	"index is out of bounds",
+	"item already exists",
 #ifndef NDEBUG
-  "quit request not honored",
-  "limits request not honored",
+	"quit request not honored",
+	"limits request not honored",
 #endif // NDEBUG
 
 };
@@ -136,30 +136,30 @@
 
 #ifndef NDEBUG
 const char bc_lang_inst_chars[] =
-  "edED_^*/%+-=;?~<>!|&`{}@[],NVMACaI.LlrOqpQsSJjPR$H";
+	"edED_^*/%+-=;?~<>!|&`{}@[],NVMACaI.LlrOqpQsSJjPR$H";
 #endif // NDEBUG
 
 const BcLexKeyword bc_lex_keywords[20] = {
-  BC_LEX_KW_ENTRY("auto", 4, true),
-  BC_LEX_KW_ENTRY("break", 5, true),
-  BC_LEX_KW_ENTRY("continue", 8, false),
-  BC_LEX_KW_ENTRY("define", 6, true),
-  BC_LEX_KW_ENTRY("else", 4, false),
-  BC_LEX_KW_ENTRY("for", 3, true),
-  BC_LEX_KW_ENTRY("halt", 4, false),
-  BC_LEX_KW_ENTRY("ibase", 5, true),
-  BC_LEX_KW_ENTRY("if", 2, true),
-  BC_LEX_KW_ENTRY("last", 4, false),
-  BC_LEX_KW_ENTRY("length", 6, true),
-  BC_LEX_KW_ENTRY("limits", 6, false),
-  BC_LEX_KW_ENTRY("obase", 5, true),
-  BC_LEX_KW_ENTRY("print", 5, false),
-  BC_LEX_KW_ENTRY("quit", 4, true),
-  BC_LEX_KW_ENTRY("read", 4, false),
-  BC_LEX_KW_ENTRY("return", 6, true),
-  BC_LEX_KW_ENTRY("scale", 5, true),
-  BC_LEX_KW_ENTRY("sqrt", 4, true),
-  BC_LEX_KW_ENTRY("while", 5, true),
+	BC_LEX_KW_ENTRY("auto", 4, true),
+	BC_LEX_KW_ENTRY("break", 5, true),
+	BC_LEX_KW_ENTRY("continue", 8, false),
+	BC_LEX_KW_ENTRY("define", 6, true),
+	BC_LEX_KW_ENTRY("else", 4, false),
+	BC_LEX_KW_ENTRY("for", 3, true),
+	BC_LEX_KW_ENTRY("halt", 4, false),
+	BC_LEX_KW_ENTRY("ibase", 5, true),
+	BC_LEX_KW_ENTRY("if", 2, true),
+	BC_LEX_KW_ENTRY("last", 4, false),
+	BC_LEX_KW_ENTRY("length", 6, true),
+	BC_LEX_KW_ENTRY("limits", 6, false),
+	BC_LEX_KW_ENTRY("obase", 5, true),
+	BC_LEX_KW_ENTRY("print", 5, false),
+	BC_LEX_KW_ENTRY("quit", 4, true),
+	BC_LEX_KW_ENTRY("read", 4, false),
+	BC_LEX_KW_ENTRY("return", 6, true),
+	BC_LEX_KW_ENTRY("scale", 5, true),
+	BC_LEX_KW_ENTRY("sqrt", 4, true),
+	BC_LEX_KW_ENTRY("while", 5, true),
 };
 
 const char bc_num_hex_digits[] = "0123456789ABCDEF";
@@ -167,21 +167,21 @@
 // This is an array that corresponds to token types. An entry is
 // true if the token is valid in an expression, false otherwise.
 const bool bc_parse_token_exprs[] = {
-  true, true, true, true, true, true, true, true, true, true, true, true, true,
-  true, true, true, true, true, true, true, true, true, true, true, true, false,
-  false, true, true, false, false, false, false, false, false, false, true,
-  true, false, false, false, false, false, false, false, true, false, true,
-  true, true, true, false, false, true, false, true, true, false, false, false,
+	true, true, true, true, true, true, true, true, true, true, true, true, true,
+	true, true, true, true, true, true, true, true, true, true, true, true, false,
+	false, true, true, false, false, false, false, false, false, false, true,
+	true, false, false, false, false, false, false, false, true, false, true,
+	true, true, true, false, false, true, false, true, true, false, false, false,
 };
 
 // These are to identify what tokens can
 // come after expressions in certain cases.
 const BcParseNext bc_parse_next_expr =
-    BC_PARSE_NEXT(3, BC_LEX_NEWLINE, BC_LEX_SEMICOLON, BC_LEX_RIGHT_BRACE);
+	BC_PARSE_NEXT(3, BC_LEX_NEWLINE, BC_LEX_SEMICOLON, BC_LEX_RIGHT_BRACE);
 const BcParseNext bc_parse_next_param =
-  BC_PARSE_NEXT(2, BC_LEX_RIGHT_PAREN, BC_LEX_COMMA);
+	BC_PARSE_NEXT(2, BC_LEX_RIGHT_PAREN, BC_LEX_COMMA);
 const BcParseNext bc_parse_next_print =
-    BC_PARSE_NEXT(3, BC_LEX_COMMA, BC_LEX_NEWLINE, BC_LEX_SEMICOLON);
+	BC_PARSE_NEXT(3, BC_LEX_COMMA, BC_LEX_NEWLINE, BC_LEX_SEMICOLON);
 const BcParseNext bc_parse_next_cond = BC_PARSE_NEXT(1, BC_LEX_RIGHT_PAREN);
 const BcParseNext bc_parse_next_elem = BC_PARSE_NEXT(1, BC_LEX_RIGHT_BRACKET);
 const BcParseNext bc_parse_next_for = BC_PARSE_NEXT(1, BC_LEX_SEMICOLON);
@@ -189,20 +189,20 @@
 
 // This is an array of data for operators that correspond to token types.
 const BcOp bc_parse_ops[] = {
-  { 0, false }, { 0, false },
-  { 1, false },
-  { 2, false },
-  { 3, true }, { 3, true }, { 3, true },
-  { 4, true }, { 4, true },
-  { 6, true }, { 6, true }, { 6, true }, { 6, true }, { 6, true }, { 6, true },
-  { 1, false },
-  { 7, true }, { 7, true },
-  { 5, false }, { 5, false }, { 5, false }, { 5, false }, { 5, false },
-  { 5, false }, { 5, false },
+	{ 0, false }, { 0, false },
+	{ 1, false },
+	{ 2, false },
+	{ 3, true }, { 3, true }, { 3, true },
+	{ 4, true }, { 4, true },
+	{ 6, true }, { 6, true }, { 6, true }, { 6, true }, { 6, true }, { 6, true },
+	{ 1, false },
+	{ 7, true }, { 7, true },
+	{ 5, false }, { 5, false }, { 5, false }, { 5, false }, { 5, false },
+	{ 5, false }, { 5, false },
 };
 
 const BcNumBinaryOp bc_program_ops[] = {
-  bc_num_pow, bc_num_mul, bc_num_div, bc_num_mod, bc_num_add, bc_num_sub,
+	bc_num_pow, bc_num_mul, bc_num_div, bc_num_mod, bc_num_add, bc_num_sub,
 };
 
 const char bc_program_stdin_name[] = "<stdin>";