2003-03-24  Michael Natterer  <mitch@gimp.org>

	* app/core/Makefile.am
	* app/core/gimpimage-preview.[ch]: moved the image preview code
	to separate files.

	* app/core/gimpimage.c: removed the functions here. Removed the
	new utility function gimp_image_previews_resize() because it
	did exactly what gimp_image_size_changed() should do. Moved
	the missing bits to gimp_image_size_changed().

	* app/core/gimplayer.c (gimp_layer_apply_mask): call
	gimp_viewable_invalidate_preview() only if we don't call
	gimp_drawable_update(). Calling them both is redundant.