Shorten ManualMapVoxelManipulator to MMVManip

src/cavegen.h

src/dungeongen.h

src/emerge.h

src/map.cpp

src/map.h

src/mapgen.h

src/mg_biome.cpp

src/mg_decoration.cpp

src/mg_decoration.h

src/mg_ore.cpp

src/mg_ore.h

src/mg_schematic.cpp

src/mg_schematic.h

src/script/lua_api/l_mapgen.cpp

src/script/lua_api/l_vmanip.cpp

src/script/lua_api/l_vmanip.h

src/treegen.cpp

src/treegen.h