Progress so far

[Richard Hughes <hughsient gmail com>]

So, not a lot of activity in gnome-color-manager repos in the last few
days. Let me explain why:

* There's no point writing a tiny library to color manage pixbuf's, it
belongs in the GDK/GTK layer
* We can't depend on lcms in GTK as we'll want other things on Windows7 and OSX.
* Nobody wanted to open the can of worms

So, for the last few evenings, I've written a mega-patch
(https://bugzilla.gnome.org/show_bug.cgi?id=606885) that adds in
GtkColorProfile, GtkColorTransform and GtkColorEngine objects to GTK,
and quite a bit of the interface code that makes all that possible.
There are many more changes to be made, but when this patch is
committed we can easily make a GtkImage that is color corrected, and
not have to worry about doing it in the application. In essence,
applications become color managed for free, and have to manually
opt-out of having pixbufs transformed by embedded profiles. This makes
things _much_ simpler.

The lcms bits are written as a GIO extension point, and it falls back
to a NOP or memcpy if lcms is not available. I've hopefully designed
the API to be efficient and easy to use (and portable to other
systems). The patch still needs a lot more upstream review, but I
wanted to keep you guys in the loop.

When this is complete, we can move onto GtkImage and start doing more
useful things. Needless to say, this will make GcmImage obsolete.

Richard.