2000-04-11  Federico Mena Quintero  <federico@helixcode.com>

	Most of this patch is based on a patch by Havoc Pennington
	(hp@redhat.com) to make GdkPixbuf's structures opaque and to
	remove the libart dependency.

	* gdk-pixbuf/gdk-pixbuf.h: Removed the public structures.
	(GdkColorspace): New enum that for now only contains
	GDK_COLORSPACE_RGB.
	(GdkPixbufDestroyNotify): New type for the pixbuf's pixels destroy
	notification function.
	(GdkInterpType): New num with interpolation types.

	* *.[ch]: Replace the libart stuff with our own stuff.

	* pixops/*.[ch]: Likewise.

	* gdk-pixbuf/gdk-pixbuf-private.h: New file with the private
	declarations of the GdkPixbuf structures.

	* gdk-pixbuf/gdk-pixbuf.c (gdk_pixbuf_new_from_art_pixbuf):
	Removed function.
	(gdk_pixbuf_get_format): Constify.
	(gdk_pixbuf_get_n_channels): Constify.
	(gdk_pixbuf_get_has_alpha): Constify.
	(gdk_pixbuf_get_bits_per_sample): Constify.
	(gdk_pixbuf_get_p...