more cleanup in make tests more work in the transition to the new error

* Makefile.am: more cleanup in make tests
* error.c valid.c parser.c include/libxml/xmlerror.h: more work
  in the transition to the new error reporting strategy.
* python/tests/reader2.py  result/VC/* result/valid/*:
  few changes in the strings generated by the validation output
Daniel
diff --git a/result/VC/DuplicateType b/result/VC/DuplicateType
index c183092..34e2c20 100644
--- a/result/VC/DuplicateType
+++ b/result/VC/DuplicateType
@@ -1,3 +1,3 @@
-./test/VC/DuplicateType:3: validity error: Definition of a has duplicate references of c
+./test/VC/DuplicateType:3: validity error : Definition of a has duplicate references of c
 <!ELEMENT a (#PCDATA | b | c | d | c)*>
                                        ^