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/tree.c b/tree.c
index 2974256..eee620b 100644
--- a/tree.c
+++ b/tree.c
@@ -6012,7 +6012,7 @@
 	if ((format) && (xmlIndentTreeOutput) &&
 	    (cur->type == XML_ELEMENT_NODE))
 	    for (i = 0;i < level;i++)
-		xmlBufferWriteChar(buf, "  ");
+		xmlBufferWriteChar(buf, xmlTreeIndentString);
         xmlNodeDump(buf, doc, cur, level, format);
 	if (format) {
 	    xmlBufferWriteChar(buf, "\n");
@@ -6167,7 +6167,7 @@
 		        (level >= 0?level+1:-1), format);
 	if ((xmlIndentTreeOutput) && (format))
 	    for (i = 0;i < level;i++)
-		xmlBufferWriteChar(buf, "  ");
+		xmlBufferWriteChar(buf, xmlTreeIndentString);
     }
     xmlBufferWriteChar(buf, "</");
     if ((cur->ns != NULL) && (cur->ns->prefix != NULL)) {
@@ -6399,7 +6399,7 @@
 	if ((format) && (xmlIndentTreeOutput) &&
 	    (cur->type == XML_ELEMENT_NODE))
 	    for (i = 0;i < level;i++)
-		xmlOutputBufferWriteString(buf, "  ");
+		xmlOutputBufferWriteString(buf, xmlTreeIndentString);
         xmlNodeDumpOutput(buf, doc, cur, level, format, encoding);
 	if (format) {
 	    xmlOutputBufferWriteString(buf, "\n");
@@ -6563,7 +6563,7 @@
 		        (level >= 0?level+1:-1), format, encoding);
 	if ((xmlIndentTreeOutput) && (format))
 	    for (i = 0;i < level;i++)
-		xmlOutputBufferWriteString(buf, "  ");
+		xmlOutputBufferWriteString(buf, xmlTreeIndentString);
     }
     xmlOutputBufferWriteString(buf, "</");
     if ((cur->ns != NULL) && (cur->ns->prefix != NULL)) {