Merge SDL 2.0.3.
Fixed conflict. Removed nonexistent file from SDL CMakeLists.txt.
Android fixes. Bump required Android SDK required for compiling to 12 due to SDL joystick code. Removed the activity finish request code, as SDLActivity should now cleanly wait for the native thread to exit.
Update SDL version in the documentation.
Fix SDL keyboard event sending on X11.
Fixed SDL build on MinGW.
Minor fix for SDL build on Raspberry Pi platform.
Merge branch 'sdl-update'