* Combine client and server man pages.
* Update unit test options and available databases in man page.
* Add `--worldname` to man page.
* Fix a bunch of places where `"Minetest"` was used directly instead of `PROJECT_NAME`.
* Disable server build by default on all operating systems.
* Make `ENABLE_FREETYPE` not fail if FreeType isn't found.
* Enable LevelDB, Redis, and FreeType detection by default.
* Remove the `VERSION_PATCH_ORIG` hack.
* Add option to search for and use system JSONCPP.
* Remove broken LuaJIT version detection.
* Rename `DISABLE_LUAJIT` to `ENABLE_LUAJIT`.
* Rename `minetest_*` variables in `version.{h,cpp}` to `g_*`.
* Clean up style of CMake files.
* use `pool.sks-keyservers.net` as keyserver as it's often more reliable
than `keyserver.ubuntu.com` as you can see with Google.
* put script to multiple lines
* build out-of-source
* use two CPUs
* make seems to fail if $(nproc) is used unlike WeeChat. ZNC has
same issue.
* mark build as failed if one job fails immediately without waiting for
all builds to finish.
* this doesn't stop jobs that didn't finish before build was marked
failed.
