Add a SELECT_SOFTPROOF_PROFILE mode to the color profile dialog and
use it to select a profile from a newly added "Soft-Proofing Profile..."
menu item in view -> color management.
Get rid of individual constructors for assign and convert, instead
have one constructor that takes a dialog type enum. No new features
yet in this commit.
Uncomment and implement the menu items and actions to invoke the
dialog. This new code also does the (alomst) right thing to linear
images, unlike the lcms plug-in.
Michael Natterer