Fixed groupmod create command logic

It would fail completely if you passed 3 arguments and the 3rd argument wasn't a parent group name. However, it is also allowed to pass a world name.
That didn't work and is fixed now. You may pass a world name too
Fixed assignment of worlds to groups

The groupmod add command didn't do it to start with
but the Group.setWorldName() had flawed logic as well.
It's working now. Per-world groups are loading properly.
Fixed ToolBox.parseWorld()

It would previously not work on world names without dimension indicator.
It now does the job properly.
Changed ChunkCreationHook to use int array ...

... instead of a byte array as that doesn't suffice to hold all possible
block IDs that are larger than 127
Fixed AIOOBE in HelpCommand

Did only apply to console().
It copied an invalid index range when you passed 1 argument only.