Swig/Python: enable comparison between mapper objects and None.
Swig/Python: enable comparison between mapper objects and None.

malloch/libmapper,malloch/libmapper,libmapper/libmapper,radarsat1/libmapper,radarsat1/libmapper,malloch/libmapper,libmapper/libmapper,libmapper/libmapper,malloch/libmapper,libmapper/libmapper,radarsat1/libmapper,malloch/libmapper,radarsat1/libmapper,libmapper/libmapper,radarsat1/libmapper,malloch/libmapper,libmapper/libmapper