* plug-ins/common/retinex.c: added this new plug-in.
  Addresses bug #135594

* plug-ins/common/plugin-defs.pl: modified accordingly.

* plug-ins/common/.cvsignore
* plug-ins/common/Makefile.am: regenerated.

* plug-ins/gfig/gfig-arc.c
* plug-ins/gfig/gfig-arc.h
* plug-ins/gfig/gfig-circle.c
* plug-ins/gfig/gfig-circle.h
* plug-ins/gfig/gfig-dialog.c: smallish style cleanups