Temporary commit; lots of test code and stuff

data/grass.png

data/stone.png

src/CMakeLists.txt

src/activeobject.h

src/client.cpp

src/client.h

src/clientobject.cpp

src/clientobject.h

src/clientserver.h

src/environment.cpp

src/environment.h

src/jthread/jmutex.h

src/main.cpp

src/map.cpp

src/map.h

src/mapblock.cpp

src/mapblockobject.cpp

src/mapnode.h

src/player.cpp

src/player.h