This makes positional audio in sdl work correctly (things to the left
    play sounds in the left speaker)

This makes positional audio in sdl work correctly (things to the left
play sounds in the left speaker)

SDL1.2 is dead, long live SDL

to avoid a crash

Should now ignore all motion events and not warp the mouse when the
window is out of focus.

Fixes Furyhunter/SRB2#1 but probably makes mouse speed too slow on
Linux. Whatever.

-softblit uses SDL2 software renderer backend for blitting

SDL_UpdateTexture is apparently not good for streaming textures.
So instead, I did SDL_LockTexture/Unlock.

GL_EXT_texture_filter_anisotropic is cool I guess

GL Initialization needs to happen before window creation,
otherwise the GL library will get reloaded while in use and
Windows will have a heart attack. This is bad, obviously.