little cleanups
cleanups one more time
WorldObjectsContainer-->WorldObjectsMaster, RenderableObjectsContainer-->RenderableObjectsMaster
cleanups
preparations: getting rid off getWorldType(), getEntityType(), getItemType
new WorldObjectType
Tile::occupants refactor first steps
refactor logic fixes
Nullable.java
WorldObjectVisitor
refactor's next stage: preparation for new collision result resolving (Visitor pattern)