doc updates from Heiko Rupp 2 sanity checks from Heiko Rupp Daniel

* libxml.4 parser.c: doc updates from Heiko Rupp
* parserInternals.c: 2 sanity checks from Heiko Rupp
Daniel
diff --git a/libxml.4 b/libxml.4
index 6b8f5ce..62d9c7d 100644
--- a/libxml.4
+++ b/libxml.4
@@ -63,4 +63,9 @@
 Manual page by Ziying Sherwin (sherwin@nlm.nih.gov),
 Lister Hill National Center for Biomedical Communications,
 U.S. National Library of Medicine.
+.SH SEE ALSO
+.IR xmllint (1),
+.IR libxslt (4),
+.IR libexslt (4),
+.IR xsltproc (1)
 .\" end of manual page