Remove gdk_screen_close, add a section for GdkDisplayManager, add

Remove gdk_screen_close, add a section for GdkDisplayManager, add

	* gdk/gdk-sections.txt: Remove gdk_screen_close, add a section
	for GdkDisplayManager, add gdk_visual_get_screen and
	gdk_colormap_get_screen.
	* gdk/gdkdisplaymanager.c:
	* gdk/gdkdisplay.c (gdk_pointer_ungrab): Fix doc comments.

	* gdk/x11/gdkcolor-x11.c (gdk_colormap_get_screen):
	* gdk/x11/gdkimage-x11.c (gdk_image_new_bitmap): Make parameter
	names match those in the header file, to silence gtk-doc.