allow checking MethodProxy type from TPython;
  for: http://root.cern.ch/phpBB3/viewtopic.php?f=14&t=15805


git-svn-id: https://root.cern.ch/svn/root/branches/v5-34-00-patches@48878 27541ba8-7e3a-0410-8455-c3a389f83636