more work on cleaning up XML Schemas datatypes based on James Clark tests

* relaxng.c include/libxml/relaxng.h xmlschemastypes.c: more work
  on cleaning up XML Schemas datatypes based on James Clark tests
  test/xsdtest/xsdtest.xml
Daniel
diff --git a/relaxng.c b/relaxng.c
index a916fda..f28869b 100644
--- a/relaxng.c
+++ b/relaxng.c
@@ -1850,7 +1850,7 @@
 	    snprintf(msg, 1000, "failed to validate type %s", arg1);
 	    break;
 	case XML_RELAXNG_ERR_TYPEVAL:
-	    snprintf(msg, 1000, "Type %s doesn't allow value %s", arg1, arg2);
+	    snprintf(msg, 1000, "Type %s doesn't allow value '%s'", arg1, arg2);
 	    break;
 	case XML_RELAXNG_ERR_DUPID:
 	    snprintf(msg, 1000, "ID %s redefined", arg1);
@@ -1912,6 +1912,10 @@
 	    snprintf(msg, 1000, "Invalid attribute %s for element %s",
 		     arg1, arg2);
 	    break;
+	case XML_RELAXNG_ERR_LACKDATA:
+	    snprintf(msg, 1000, "Datatype element %s contains no data",
+		     arg1);
+	    break;
 	case XML_RELAXNG_ERR_DATAELEM:
 	    snprintf(msg, 1000, "Datatype element %s has child elements",
 		     arg1);