[Python] Adds a convenience dialog. Dialog.notification()

@jimfcaroll, this patch works as is, but it would be nice to add the three default notification images as constants to xbmcgui module.

I tried your directions, but no matter what I tried. swig kept casting it to an int.


PyModule_AddStringConstant(module,"NOTIFICATION_INFO",(int)getNOTIFICATION_INFO());