More control over ingame allying

[CarRepairer]

As some people may know, I've been working on a ceasefire control panel (in CA) which has made for some super fun FFA games.

But I would like to request that some engine changes are made to give me more control over the /ally command because right now it's a bit messy.

1) Let me set ingame allies in luarules.

and/or

2) Enable me to disallow someone using the /ally command (or any command) in luarules, even when Fixed Ingame Alliances is unchecked.

One or both of the above would be helpful.

[imbaczek]

sensible ideas; put both on mantis, in separate issues.