Gang Mode for TG

# This adds my first playable version of Gang Mode for TG. (aka Rev vs Rev)
- 2 or 4 players will be selected to be the bosses of two different gangs.
- They will be able to convert via flashing
- Gangsters (converted crewmembers) will only be able to see the icon of their bosses
  - Gang bosses will be able to see icons for everyone in their gang
- Gang bosses are supplied with a shuttle recaller that can recall the shuttle from anywhere on-station
  - Recallers still need to be used before the point of no return
  - Recallers will send a tracable signal, and communications consoles can know where they come from
- Gangsters can be reformed (de-converted) by striking them at their head a good few times

### Round-Ending Conditions:
- Gang Victory: The opposing gang's bosses are all dead/off-station/non-human
- Station Victory: The station is successfully evacuated

### Differences from Rev:
- Symmetrical sides (rev vs rev, rather than rev vs security)
- Heads can be converted (But cannot start as a gang boss)
- Loyalty implants block conversions, but will not de-convert those who are already gangsters
- Not always knowing who is with which gang
- Lack of membership visibility encourages gangs to stick together and work as a group to avoid friendly fire
- Evacuation as a possible round-ending condition

This has been tested on a locally hosted server of 10 players and it's been found to be bug-free (as far as we could tell).

***However, I ask that admins do not add this to rotation, and do not run it unless I am online to observe the events. The game mode has yet to be fully playtested live, and carries with it a very high risk of it being boring/stupid/buggy as shit.***