Merge branch SRB2:next into io_openlump-alladdons

.circleci/config.yml

.gitattributes

.gitignore

.gitlab-ci.yml

CMakeLists.txt

CMakePresets.json

appveyor.yml

cmake/CPM.cmake

cmake/Comptime.cmake

comptime.bat

comptime.sh

extras/conf/udb/Includes/SRB222_linedefs.cfg

libs/SDL2/WhatsNew.txt

libs/SDL2/cmake/sdl2-config-version.cmake

libs/SDL2/cmake/sdl2-config.cmake

libs/SDL2/docs/CONTRIBUTING.md

libs/SDL2/docs/README-android.md

libs/SDL2/docs/README-cmake.md

libs/SDL2/docs/README-directfb.md

libs/SDL2/docs/README-dynapi.md