Return existing signal in the case that mdev_add_* uses existing signal name.
Return existing signal in the case that mdev_add_* uses existing signal name.

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