* gimp/plug-ins/jpeg/gimpexif.c
	* gimp/plug-ins/jpeg/gimpexif.h: new files with prototype
	interface code for metadata system.

	* gimp/plug-ins/jpeg/Makefile.am
	* gimp/plug-ins/jpeg/jpeg-exif.c
	* gimp/plug-ins/jpeg/jpeg.c: adapted to metadata interface
	as described on gimp-dev mailing list.