Merge branch 'slight-shader-cleanup' into 'next'

src/hardware/hw_defs.h

src/hardware/hw_drv.h

src/hardware/hw_main.c

src/hardware/hw_main.h

src/hardware/hw_md2.c

src/hardware/r_opengl/r_opengl.c

src/sdl/hwsym_sdl.c

src/sdl/i_video.c

src/w_wad.c