gtk.go: Added new wrapper for gtk_file_chooser_set_current_name.
gtk.go: Added new wrapper for gtk_file_chooser_set_current_name.

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