fixed to not send NULL to %s printing cleaning up some of the regression

* HTMLparser.c: fixed to not send NULL to %s printing
* python/tests/error.py result/HTML/doc3.htm.err
  result/HTML/test3.html.err result/HTML/wired.html.err
  result/valid/t8.xml.err result/valid/t8a.xml.err: cleaning
  up some of the regression tests error
Daniel
diff --git a/result/valid/t8.xml.err b/result/valid/t8.xml.err
index fa56316..7ae7bb4 100644
--- a/result/valid/t8.xml.err
+++ b/result/valid/t8.xml.err
@@ -1,4 +1,5 @@
-Entity: line 1: parser error : internal error %defroot; 
+Entity: line 1: parser error : internal error
+ %defroot; 
           ^
 Entity: line 1: 
 <!ELEMENT root (middle) >