-Added Support for planes

-Added support for planes

Slew to Grid:
-Improved accuracy
-Now slews to center of grid
-Added proper cancel functionality via escape key
-Set focus to text input when dialog comes up for faster input
-Users can now commit their entry with the Enter key on the numpad for faster input
-Tooltip added to Enter key to remind users of keyboard inputs

-Added slew to typed coordinates feature. Initial implementation can be off by approx 100 meters - researching cause.

-Automatic turret unlocking once slewing is complete
-Initial Support for planes (single seaters won't see the marker and slew commands yet)

-Updated so that ONLY turret operators see the Slew and marker actions. Sadly, incompatible with CUP at the moment.

-Minor bugfix

-Removed bug where each subsequent map click after slewing the turret would result in another "uncommanded" slew operation

-Re-wrote main loop to prevent "infinate loading screen" (also acted as a performance improvement)

-Added target grid indicator
-Should now work on all helicopters
-Made North S.A. pointer more accurate
-Filtered out FFV "turrets". Gunners on littlebird benches should no longer see the North marker or interface.