Prevent PyXML from importing, causing crashes

http://seclists.org/nmap-dev/2014/q2/318

Essentially, we import the xml name, then override its search path,
stripping out the _xmlplus paths that PyXML uses. This leaves only the
Python 2 standard library path, which is what Zenmap was written for.

zenmap/zenmapGUI/MainWindow.py

@@ -125,6 +125,11 @@ import gtk
 import sys
 import os
 from os.path import split, isfile, join, abspath, exists
+
+# Prevent loading PyXML
+import xml
+xml.__path__ = [x for x in xml.__path__ if "_xmlplus" not in x]
+
 import xml.sax.saxutils
 
 from time import time