Merge branch SRB2:next into slopecontrast-fix

cmake/Modules/Findlibopenmpt.cmake

src/am_map.c

src/d_main.c

src/dedicated/i_system.c

src/deh_soc.c

src/dehacked.c

src/dehacked.h

src/hardware/hw_md2.c

src/hardware/r_opengl/ogl_win.c

src/hardware/r_opengl/r_opengl.c

src/hardware/r_opengl/r_opengl.h

src/m_menu.c

src/netcode/mserv.c

src/netcode/mserv.h

src/p_mobj.c

src/sdl/i_system.c

src/sdl/i_video.c

src/sdl/ogl_sdl.c

src/sdl/ogl_sdl.h