* Move included json code to jsoncpp subdirectory
This is needed to avoid having to specify the minetest src directory
as a system include when fixing the json includes.
* Fix json includes
They used "", so that the compiler searches the project's directory
first. The result was that when compiling with a system jsoncpp,
the project's own version of json.h was still included, instead of
the system version.
The includes now use <>, so a system location, or one specified with
'-Ilocation' is searched only.
* Fix for jsoncpp deprecated function warning
When compiling with a newer version of jsoncpp (and
ENABLE_SYSTEM_JSONCPP=true), jsoncpp emits a warning
about a deprecated function that minetest uses.
* 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.
