C++ headers: Moved Db::Device and Db::Signal iterators from abstract class to Db::<thing> class.
C++ headers: Moved Db::Device and Db::Signal iterators from abstract class to Db::<thing> class.

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