Merge remote-tracking branch 'origin/master'

builtin/builtin.lua

builtin/chatcommands.lua

builtin/features.lua

client/shaders/test_shader_3/base.txt

client/shaders/test_shader_3/opengl_fragment.glsl

client/shaders/test_shader_3/opengl_vertex.glsl

doc/lua_api.txt

minetest.conf.example

po/no/minetest.po

src/camera.cpp

src/cavegen.cpp

src/cavegen.h

src/client.cpp

src/client.h

src/clientserver.h

src/content_abm.cpp

src/content_mapblock.cpp

src/content_sao.cpp

src/defaultsettings.cpp

src/environment.cpp