Add signal's user_data field to the list of queriable properties.
Add signal's user_data field to the list of queriable properties.

radarsat1/libmapper,davidhernon/libmapper,libmapper/libmapper,malloch/libmapper,malloch/libmapper,johnty/libmapper,libmapper/libmapper,johnty/libmapper,radarsat1/libmapper,davidhernon/libmapper-admin2,radarsat1/libmapper,malloch/libmapper,davidhernon/libmapper,davidhernon/libmapper,davidhernon/libmapper-admin2,davidhernon/libmapper,malloch/libmapper,libmapper/libmapper,johnty/libmapper,libmapper/libmapper,davidhernon/libmapper,johnty/libmapper,radarsat1/libmapper,libmapper/libmapper,davidhernon/libmapper-admin2,davidhernon/libmapper-admin2,davidhernon/libmapper-admin2,johnty/libmapper,radarsat1/libmapper,malloch/libmapper,malloch/libmapper,libmapper/libmapper