AGM_SwitchUnits, Insurgency-esque unit switching

SwitchUnits is a module that enables the ability for one side to switch to AI units. In a way it was possible in obviously the best!!! Arma 2 / ACE Mission: Insurgency by Fireball.

Allowing other players to perform as enemies even during a coop mission increases the *authenticity* of the enemy (hence my idea of maybe adding it it to AGM).

The greatest USP of having this as a module is, that existing (dynamic) missions (Enemy Assault, Patrol Ops, Invade & Annex etc...) don't need to be reworked to add all dynamicly spawned units as curator units and control them as Zeus. It would just be: drop in the module, choose the side and you'd be ready to go.

![2014-10-13_00001](https://cloud.githubusercontent.com/assets/1235520/4609827/984c6c3e-52a6-11e4-9803-beb75140d9ed.jpg)


![2014-10-13_00002](https://cloud.githubusercontent.com/assets/1235520/4609828/9c95049a-52a6-11e4-85db-117e724b612a.jpg)



In it's current state it gives all players of a side the ability to control AI.

**Todo:**
- [ ] Sync playable units to the module
- [ ] Don't allow switching when in n meters around the opposing side
- [ ] Restrict to player names / ID's (?)
- [ ] Add ratio of players vs. enemy players
- [ ] Test it in MP
Stacking handle damage should be tested. I think this could break medical. Also, I don't know who did this first, but handle damage should return number (the damage, e.g. 0) not bool.