gdk3: add declaration Init_gdk_device_manager
gdk3: add macro to treat GDK object
gdk3: implement Gdk::Device#get_position and Gdk::Device#warp Gdk::Device#grab
gdk3: implement Gdk::Window#get_device_position
gdk3: add deprecation methods to deprecated.rb
gtk3: remove trailing spaces
gtk3: add deprecation methods to deprecated.rb
gdk3: use GOBJGLIST2RVAL_FREE() instead
gdk3: remove unneeded implement API
gdk3: remove trailing spaces
gdk3: remove obsolete API