Distributed: Add support for sending d-objects

Technical Description:
- Server can currently send DistributedObjects now, clients cannot
receive (yet).
- InternalPacket6DistributedObjectCreation
- Added DistributedObject#toString which returns a String that can be
used for parsing the DO
- Switched all get*ValueKeys in DistributedObject from protected ->
public
- UnknownClient#getServer added