OpenCS settings

The Subview section is not yet implemented, but I would like people to try it out and provide feedback comments please.  There are some debug statements still in there, please ignore them ;-)

Unfortunately I couldn't make use of existing settings code by graffy76 (couldn't work out how to use the settings framework with Qt Designer generated header file)
CG should not be a user-visible option, as it's not fully supported on all systems. It can stay in the settings backend for developer testing purposes, but should not be an advertised option. If that is not possible due to design of the user settings system, then just remove the option entirely.