TreeSelection: increase refcount when wrapping a pointer
TreeSelection: increase refcount when wrapping a pointer

rust-gnome/gtk,LordSentox/gtk,EPashkin/rust-gnome-gtk,drewet/gtk,daa84/gtk,daa84/gtk,insanebits/gtk,Susurrus/gtk,drewet/gtk,gkoz/rust-gnome-gtk,gkoz/gtk-rs-gtk,rust-gnome/gtk,insanebits/gtk,gkoz/rust-gnome-gtk,mitaa/gtk,EPashkin/rust-gnome-gtk,LordSentox/gtk,mitaa/gtk,gkoz/gtk-rs-gtk,Susurrus/gtk