* app/composite/make-gimp-composite-dispatch.py: big code cleanup.

* app/composite/Makefile.am: removed references to $(builddir)

* app/composite/test-composite.c: cleanup, preparation for transition to
automatically generated regression testing code.

* app/composite/gimp-composite.c: Clean up of typedef usage

* app/composite/gimp-composite-regression.[ch]: added foundation
for regression testing.