Restore CurAmmoType check as well, that was removed in
r8f317ba10675 when trying to fix aiming during alt attack.
This probably fixes
bug #657
Hedgewars.png had a resolution more than twice as high as required; also fixed some (mostly obsolete) code that also contained a typo that would cause a warning/note in clang
move sdlmain_osx aside in its own folder so its include path is not contaminated