enhanced macros to avoid breaking ABI from previous versions. modified to

* genChRanges.py, chvalid.c, include/libxml/chvalid.h,
  include/libxml/parserInternals.h: enhanced macros to avoid
  breaking ABI from previous versions.
* catalog.c, parser.c, tree.c: modified to use IS_* macros
  defined in parserInternals.h.  Makes maintenance much easier.
* testHTML.c, testSAX.c, python/libxml.c: minor fixes to avoid
  compilation warnings
* configuration.in: fixed pushHTML test error; enhanced for
  better devel (me) testing

testHTML.c

@@ -78,10 +78,11 @@ xmlSAXHandler emptySAXHandlerStruct = {
     NULL, /* getParameterEntity */
     NULL, /* cdataBlock */
     NULL, /* externalSubset */
-    1,
-    NULL,
-    NULL,
-    NULL
+    1,    /* initialized */
+    NULL, /* private */
+    NULL, /* startElementNsSAX2Func */
+    NULL, /* endElementNsSAX2Func */
+    NULL  /* xmlStructuredErrorFunc */
 };
 
 xmlSAXHandlerPtr emptySAXHandler = &emptySAXHandlerStruct;
@@ -604,6 +605,7 @@ xmlSAXHandler debugSAXHandlerStruct = {
     1,
     NULL,
     NULL,
+    NULL,
     NULL
 };