Merge remote-tracking branch 'Furyhunter/sdl2' into sdl2
change SDL into HAVE_SDL
doh, I forget one, and in SDL2's Makefile.cfg
sdl2: oops it should be 32 bpp in softblit
sdl2: add -borderless option for windowed
Initial uncapped framerate support

THIS WILL BREAK COMPILATION ON EVERYTHING EXCEPT SDL2.