GCMD Improvements

[Wild1145]

This issue combines a few currently open issues around the changes to the GCMD System.

• The addition of a potential black list to the GCMD command system to stop potentially abusive commands from being able to be executed through another admin, (Original Issue: Gcmd command blacklist #1905)
• The ability to GCMD someone to GCMD someone else should be blocked (Original Issue Gcmd command blacklist #1905)
• Disable the usage of GCMD from console (Original Issue: Block GCMD from Console #1899)
• Display a "Ghost" message to the player being GCMD'd to say who originally GCMD'd them and ensure that it is logged as such in the logs (Original Issue: Message for /gcmd #1900)

As all these issues are similar in that they are trying to improve the command I feel that actually they would work well together in one issue so we can discuss everything relating to that command here. If anyone has any suggestions / input please do let me know.

Current PR #1911