2004-07-21  Michael Natterer  <mitch@gimp.org>

	Enabled the various "Clear saved foobar now" buttons in prefs:

	* app/gui/session.[ch]
	* app/menus/menus.[ch]
	* app/widgets/gimpdevices.[ch]: implemented the _clear()
	functions: unlink() the rc file and set an internal flag that it
	has been deleted. Added "gboolean always_save" parameter to the
	_save() functions and don't save anything if it is FALSE and the
	internal deletion flag has been set.

	* app/gui/gui.c
	* app/widgets/gimpdevicestatus.c: changed accordingly.

	* app/gui/preferences-dialog.c: added callbacks for all "Save now"
	and "Clear now" buttons and show error messages if clearing fails.
	Inform the user that she has to restart GIMP to see the effect of
	the clearing.