Fixes bug where selection text and ammo graphic would disappear on failed unload
- Fixed not loading MIDIs properly.
- Fixed no error when audio files are missing.
- Fixed audio file priority (no longer need to delete GM.CAT).
- Fixed "mute" setting causing crashes.
WIP Controls stuff.
- Fixed used hangars miscounting crafts in production.
- Fixed misleading function name.
Fix map view of desert hills
Fix hidden aliens on top of slopes in map
bin/data/Language/Polish.lng
fixing compilation errors on Linux

directory and file names are case sensitive!
std::cerr requires an #include
Merge pull request #273 from hmaon/seriously

fixing compilation errors on Linux
Merge remote-tracking branch 'upstream/master' into unloadTextFix
Merge pull request #272 from redx25/unloadTextFix

Minor inventory bug fix
Merge pull request #274 from radius75/Polish.lng

bin/data/Language/Polish.lng