2003-02-12  Michael Natterer  <mitch@gimp.org>

	Moved the undo system to the core: Keep GimpUndoStack objects as
	undo and redo stack. Use GimpUndo objects as members of the
	stacks. GimpUndoStack is derived from GimpUndo and keeps undo
	groups, so undo group handling is much simpler than before
	(the whole group is just a single GimpUndo object on the
	stack and not everything between group boundary markers).

	* app/Makefile.am
	* app/undo_types.h: removed.

	* app/config/gimpcoreconfig.[ch]: added "gulong undo_size".
	* app/config/gimprc-blurbs.h: and its blurb.

	* app/core/core-enums.[ch]: added GimpUndoMode and GimpUndoType.

	* app/core/core-types.h: removed UndoType, added GimpUndoAccumulator,
	GimpUndoPopFunc and GimpUndoFreeFunc.

	* app/core/gimpundo.[ch]: do everything the old "Undo" struct did.
	Removed the virtual push() function and added free().

	* app/core/gimpundostack.[ch]: keeps the new undo/redo stacks
	and also acts as undo group.

	* app/core/gimpimage-undo.[ch]: moved the undo apparatus here.

	* app/core/gimpimage.[ch]: removed the old stuff.

	* app/core/gimpmarshal.list: added marshaller needed for GimpUndo.

	* app/undo.[ch]: removed the whole undo mechanism. Only the
	actual undo pushing functions are left.

	* app/undo_history.c
	* app/gui/edit-commands.c
	* app/gui/file-commands.c
	* app/gui/image-menu.c
	* app/gui/preferences-dialog.c
	* app/tools/gimpeditselectiontool.c: changed accordingly.