Merge branch 'master' into sdl2

Conflicts:
	Makefile
	code/renderercommon/qgl.h
	code/renderergl1/tr_local.h
	code/sdl/sdl_glimp.c
Merge branch 'master' into sdl2

Conflicts:
	code/sdl/sdl_input.c
SDL2 libs for OSX, thanks to MAN-AT-ARMS
Update prebuilt SDL2 libs for Windows
More updates to SDL2 libs from MAN-AT-ARMS
Update SDL2 headers... oops
Merge remote-tracking branch 'ioquake3/sdl2' into sdl2

Conflicts:
	Makefile
	code/renderergl1/tr_local.h
	code/sdl/sdl_input.c