added SetActiveID and GetModel for GtkComboBox
added SetActiveID and GetModel for GtkComboBox

yamnikov-oleg/gotk3,pekim/gotk3,pekim/gotk3,andre-hub/gotk3,andre-hub/gotk3,andre-hub/gotk3,pekim/gotk3,yamnikov-oleg/gotk3,gotk3/gotk3,yamnikov-oleg/gotk3,gotk3/gotk3