0.23 swings

After trashing code for a more generic colour rendering core, my gtk development tree is again up and ready.

As usual some colour improvements are included. This means Oyranos is spread more and more over the code. I slowly export CinePaint’s colour management to Oyranos. So, CinePaint must at some point rely on it to build. Otherwise I have to provide the bits in two places. The Oyranos dependency will turn mandatory probably already in the 0.23 release.

As well, CinePaint should build by default as a Gtk2 app. Some distribution try to fake the old Gtk1 API by some none useable headers to finally link into Gtk2. As this is non sense for a advanced application like CinePaint, consequently many users experienced failing builds. The configure option -enable-gtk1 should turn the old build mode after the switch.