Merge remote branch 'origin/master'

builtin/serialize.lua

doc/lua_api.txt

old/Makefile.bak

po/du/minetest.po

src/CMakeLists.txt

src/camera.cpp

src/camera.h

src/client.cpp

src/client.h

src/clientserver.h

src/collision.cpp

src/collision.h

src/content_cao.cpp

src/content_sao.cpp

src/emerge.cpp

src/game.cpp

src/guiConfigureWorld.cpp

src/guiConfirmMenu.cpp

src/guiCreateWorld.cpp

src/guiDeathScreen.cpp