Add dummy and LevelDB database backends
Make it compile
Add message that LevelDB is not supported on Windows
Use STL containers instead of irr::core::list
Fix 'Unknown map backend' error when using Configure menu right after creating world
Add note about --migrate only working with minetestserver or --server
Make --migrate update world.mt too
Prevent ModMgr from deleting backend setting in world.mt
Merge remote-tracking branch 'proller/next_tools' into next
Merge remote-tracking branch 'sfan5/leveldb' into next
Merge remote-tracking branch 'proller/liquid63' into next
Merge remote-tracking branch 'proller/math' into next
Merge remote-tracking branch 'proller/json' into next
Merge remote-tracking branch 'proller/weather' into next
Merge remote-tracking branch 'proller/liquid_send' into next
Merge remote-tracking branch 'proller/liquid_default' into next
Merge remote-tracking branch 'proller/huge_cave' into next
Merge remote-tracking branch 'proller/weather_fog' into next
Merge remote-tracking branch 'proller/wingsuit' into next
Merge remote-tracking branch 'proller/collision' into next