Adds a simulation_bpc and simulation_intent to GimpImage to allow
plug-ins to access it
for CMYK import/export.
Four pdb functions were added to enable this access:
image_get_simulation_bpc (), image_set_simulation_bpc (),
image_get_simulation_intent (), and image_set_simulation_intent ().
Next, it updates menu options and code to support GimpImage's
internal simulation intent and bpc.
New 'simulation-intent-changed' and 'simulation-bpc-changed signal
are emitted via
GimpColorManagedInterface so that relevant tools
(such as the
CYMK color picker, GimpColorFrame, and future pop-overs)
are aware of these changes.