Description:
------------
SimpleXML's validate_schema_file() method is completely 
broken.

Reproduce code:
---------------
$s = simplexml_load_file('library.xml');

if ($s->validate_schema_file('library.xsd')) {
  print "valid\n";
} else {
  print "invalid\n";
}

Expected result:
----------------
Should return true when it validates and false when it 
doesn't.

Actual result:
--------------
Always return false.

This patch fixes many problems:

http://www.trachtenberg.com/patches/
simplexml_schema_patch.txt