2002-05-22  Michael Natterer  <mitch@gimp.org>

	* app/config/gimpconfig.[ch]: added virtual interface methods
	serialize_property() and deserialize_property() which can be used
	to implement (de)serialization of special properties or to
	override the default implementation.

	* app/config/gimpconfig-deserialize.c
	* app/config/gimpconfig-serialize.c: for each property, check if
	the class which added it implements the virtual functions and call
	them before trying the default implementations.

	* app/config/gimpconfig-params.h: added new macro
	GIMP_CONFIG_INSTALL_PROP_OBJECT().

	* app/core/gimpcontext.c: declare the "tool", "brush", "pattern",
	"gradient" and "palette" properties as serializable and added
	implementations of (de)serialize_property().