value-invert from the workshop to be official operations for the
next release.
* configure.ac: added enhance Makefile.am
* operations/Makefile.am: added enhance subdir
* operations/enhance/: added directory.
* operations/enhance/Makefile.am: added
* operations/workshop/bilateral-filter.c: moved ...
* operations/enhance/bilateral-filter.c: ... here
* operations/workshop/snn-mean.c: moved ...
* operations/enhance/snn-mean.c: ... here
* operations/workshop/contrast-curve.c: moved ...
* operations/color/contrast-curve.c: ... here
* operations/workshop/mono-mixer.c: moved ...
* operations/color/mono-mixer.c: ... here
* operations/workshop/value-invert.c: moved ...
* operations/color/value-invert.c: ... here

svn path=/trunk/; revision=1705