more work on XML Schemas datatypes and facets support. Currently only

* relaxng.c xmlschemastypes.c: more work on XML Schemas datatypes
  and facets support. Currently only schemas with binHex or
  base64 don't compile. A few error left in the test suite:
  found 1035 test instances: 919 success 23 failures
  most are gdate or gdateyear failing check, and a few cases where
  James clark tests results are strange.
* valid.c: allow to reuse the Notation checking routine without
  having a validation context.
* SAX.c: removed a #if 0
Daniel
diff --git a/valid.c b/valid.c
index ee2e678..84d63b1 100644
--- a/valid.c
+++ b/valid.c
@@ -2977,7 +2977,7 @@
     if ((notaDecl == NULL) && (doc->extSubset != NULL))
 	notaDecl = xmlGetDtdNotationDesc(doc->extSubset, notationName);
 
-    if (notaDecl == NULL) {
+    if ((notaDecl == NULL) && (ctxt != NULL)) {
 	VERROR(ctxt->userData, "NOTATION %s is not declared\n",
 	       notationName);
 	return(0);