Added ForEachLoadedChunk Callback

Added https://github.com/mc-server/MCServer/issues/1156

The lines are not right with spaces and tabs. How can i fix it?
This won't work, unfortunately. You'll need to create a `cItemCallback2` template that takes two params. And that means even more problems, because then you can't take the easy path in the ManualBindings, you'll end up duplicating even more code.