Expose sector flags to Lua and UDMF

extras/conf/udb/Includes/SRB222_misc.cfg

src/deh_lua.c

src/deh_tables.c

src/deh_tables.h

src/lua_maplib.c

src/p_map.c

src/p_mobj.c

src/p_polyobj.c

src/p_setup.c

src/p_spec.c

src/r_defs.h