Merge branch 'master' into gametype-refactor

.circleci/config.yml

.gitattributes

.gitignore

.gitlab-ci.yml

appveyor.yml

cpdebug.mk

extras/conf/SRB2-22.cfg

extras/conf/udb/Includes/SRB222_things.cfg

src/Makefile

src/Makefile.d/detect.mk

src/Makefile.d/features.mk

src/Makefile.d/nix.mk

src/config.h.in

src/d_clisrv.c

src/d_main.c

src/d_netcmd.c

src/d_netcmd.h

src/deh_lua.c

src/deh_tables.c

src/deh_tables.h