Warzone 2100 Graphic Mods tools

Code change again.

Fix to shield bar on linux systems.

Change shield bar, add colour scale as shield strength decreases.

Added polka dots to bar.

Changed shield bar from yellow to Cyan.

Fix: sound capture was not being stopped properly when max frame count
was exceeded.

Cleanup: remove unused cruft from opeanal_track.

change colour again

Added more comments for code readability.

update field texture

adding frontend0.png change and forcefield colour change