Merge remote-tracking branch 'upstream/master' into shaders-222

# Conflicts:
#	src/hardware/r_opengl/r_opengl.c
#	src/i_video.h
#	src/r_main.c
#	src/r_main.h
#	src/screen.c
#	src/sdl/i_video.c
#	src/sdl/ogl_sdl.c
#	src/w_wad.c