Refactor the lexer's string code
This makes it a vector to use vector code.
diff --git a/src/num.c b/src/num.c
index 81efb8a..d1b8989 100644
--- a/src/num.c
+++ b/src/num.c
@@ -860,7 +860,7 @@
while (intp.len) {
if ((status = bc_num_mod(&intp, base, &digit, 0))) goto frac_len_err;
if ((status = bc_num_ulong(&digit, &dig))) goto frac_len_err;
- if ((status = bc_vec_push(&stack, &dig))) goto frac_len_err;
+ if ((status = bc_vec_push(&stack, 1, &dig))) goto frac_len_err;
if ((status = bc_num_div(&intp, base, &intp, 0))) goto frac_len_err;
}