Implement blend modes

src/d_clisrv.c

src/d_clisrv.h

src/dehacked.c

src/f_wipe.c

src/hardware/hw_defs.h

src/hardware/hw_draw.c

src/hardware/hw_light.c

src/hardware/hw_main.c

src/hardware/hw_main.h

src/hardware/hw_md2.c

src/hardware/r_opengl/r_opengl.c

src/lua_mobjlib.c

src/p_mobj.c

src/p_mobj.h

src/p_saveg.c

src/r_data.c

src/r_draw.c

src/r_draw.h

src/r_main.c

src/r_plane.c