* app/core/gimpguide.c
	* app/core/gimpguide.h: new files, implementing GuideGimp as a GimpObject

	* app/core/Makefile.am: add new files as sources

	* app/core/gimpimage-guides.h
	* app/core/gimpimage-guides.c: use the new object instead of defining
	GimpGuide here as a struct.

	* app/core/gimpimage-crop.c
	* app/core/gimpimage-duplicate.c
	* app/core/gimpimage-flip.c
	* app/core/gimpimage-resize.c
	* app/core/gimpimage-rotate.c
	* app/core/gimpimage-scale.c
	* app/core/gimpimage-snap.c
	* app/core/gimpimage-undo-push.c
	* app/core/gimpimage.c
	* app/display/gimpdisplayshell-draw.c
	* app/display/gimpdisplayshell.c
	* app/pdb/guides_cmds.c
	* app/tools/gimpmovetool.c
	* app/xcf/xcf-save.c
	* tools/pdbgen/pdb/guides.pdb: include "core/gimpguide.h", and use
	g_object_ref/unref instead of gimp_image_guide_ref/unref.