Maya: 1. Changed the way userSetup.py is called. New execution chain: MAYA_SCRIPT_PATH has path to userSetup.mel --> userSetup.mel appends global_variables.MAYA_USERSETUP_PATH to sys.path and imports userSetup.py. 2. Added MAYA_USERSETUP_PATH to global_variables 3. Only global_variables.MAYA_PYTHONPATH_LIST is added to pythonpath. No more maya directories in houdinis interpreter sys.path for example. Pathes for interpreters of the different DCCs are now cleanly separatable.