Add Mapgen V7, reorganize biomes

.gitignore

games/minimal/mods/default/init.lua

src/CMakeLists.txt

src/biome.cpp

src/biome.h

src/defaultsettings.cpp

src/emerge.cpp

src/emerge.h

src/mapgen.cpp

src/mapgen_v7.cpp

src/mapgen_v7.h

src/noise.cpp

src/noise.h

src/scriptapi.cpp

src/server.cpp

src/server.h