Cosa è cambiato in EDuke32, build per build

Add SDL2 headers and libraries to the repo for quick-and-easy building and static linking. (SDL2 uses the zlib license so we are in the clear.)

allow desktop-sized windowed modes, add 1680x1050 to defaults list.

make the crash log file named eduke32_or_mapster32.crash.log.

Add the default installation paths for the GOG.com release of Duke Nukem 3D: Atomic Edition and the Steam release of Duke Nukem 3D: Megaton Edition (if they exist) to EDuke32's search path.