apply a couple of patches from Christian Cornelssen fixing the man pages

* libxml.3 doc/buildDocBookCatalog: apply a couple of patches
  from Christian Cornelssen fixing the man pages and the Catalog
  building script.
* xmlschemas.c include/libxml/schemasInternals.h: nothing new yet
  next step is <xs:import> I now have a reasonable understanding
  of how it works.
Daniel
diff --git a/libxml.3 b/libxml.3
index 62d9c7d..18a743a 100644
--- a/libxml.3
+++ b/libxml.3
@@ -1,4 +1,4 @@
-.TH libxml 4 "12 April 2000"
+.TH libxml 3 "12 April 2000"
 .SH NAME
 libxml \- library used to parse XML files
 .SH DESCRIPTION
@@ -65,7 +65,7 @@
 U.S. National Library of Medicine.
 .SH SEE ALSO
 .IR xmllint (1),
-.IR libxslt (4),
-.IR libexslt (4),
+.IR libxslt (3),
+.IR libexslt (3),
 .IR xsltproc (1)
 .\" end of manual page