Introducting soft-proofing and Black Point Compensation, simplify the

CMM at the end of the pipeline + sparse code refactoring
A new BPC checkbutton has been created in 'Preferences/Color Management'
and in the ICM tool. Better hanbling of widget sensitivity of the output
profile / gamma part of the ICM tool.

rtgui/preferences.h

@@ -97,6 +97,7 @@ protected:
     Gtk::FileChooserButton* iccDir;
     Gtk::ComboBoxText* monProfile;
     Gtk::ComboBoxText* monIntent;
+    Gtk::CheckButton* monBPC;
     Gtk::CheckButton* cbAutoMonProfile;
     //Gtk::CheckButton* cbAutocielab;
     Gtk::CheckButton* cbciecamfloat;