added Datatype ID and IDREF, usable from RelaxNG now need to add a new

* relaxng.c valid.c xmlschemastypes.c: added Datatype ID
  and IDREF, usable from RelaxNG now
* include/libxml/xmlschemastypes.h: need to add a new interface
  because the validation modifies the infoset
* test/relaxng/testsuite.xml: extended the testsuite
Daniel
diff --git a/valid.c b/valid.c
index 4a978c3..491e5d4 100644
--- a/valid.c
+++ b/valid.c
@@ -5988,6 +5988,7 @@
  *
  * basically it does the following checks described by the XML Rec
  * 
+ * Check all the IDREF/IDREFS attributes definition for validity
  *
  * returns 1 if valid or 0 otherwise
  */