Merge branch 'udmf-next' of https://git.magicalgirl.moe/STJr/SRB2/ into udmf-multitag

# Conflicts:
#	src/hardware/hw_main.c
#	src/p_ceilng.c
#	src/p_floor.c
#	src/p_mobj.c
#	src/p_mobj.h
#	src/p_polyobj.c
#	src/p_saveg.c
#	src/p_setup.c
#	src/p_spec.c
#	src/p_spec.h
#	src/p_user.c
#	src/r_bsp.c
#	src/r_defs.h