Tab completion packet is handled and sent.

This only handles the network comm and the overall design logic, the actual completion is not yet implemented, only dummy values are returned for now.
Implemented the actual tab completion for commands and playernames.

Each command is reported only if the player has the permission to use it.
ProtoProxy: Added the tab completion packet parsing
ProtoProxy: Tab completion logging lists the last item, too
Merge branch 'tabcompletion'