changed default value for global parameter xmlIndentTreeOutput to 1 and

* global.data globals.c tree.c include/libxml/globals.h                         win32/libxml2.def.src win32/dsp/libxml2.def.src: changed                        default value for global parameter xmlIndentTreeOutput to 1 and                 introduced new global parameter xmlTreeIndentString (the string                 used to do one-level indent) with default value "  " (as it was                 in tree.c)
diff --git a/global.data b/global.data
index f7d5d00..43d2fb5 100644
--- a/global.data
+++ b/global.data
@@ -8,6 +8,7 @@
 void *,xmlGenericErrorContext
 int,xmlGetWarningsDefaultValue
 int,xmlIndentTreeOutput
+const char *,xmlTreeIndentString
 int,xmlKeepBlanksDefaultValue
 int,xmlLineNumbersDefaultValue
 int,xmlLoadExtDtdDefaultValue