Improve PBW compatibility.

[DaloLorn]

The Tactical Turn concept from #3 is nice, but not quite compatible with the goals of a proper PBW system. TTs assume that players will tend to play more or less simultaneously, while PBW's greatest advantage is that it doesn't care if people can't play simultaneously, it'll still work just fine.

So, while this is definitely not a primary focus, I should do it eventually:

• Implement autoresolve for combat. This can probably be done by simply handing control over to the AI and fast-forwarding through the thing as quickly as safely possible.
• Perhaps implement SE5-style simultaneous turns as an option, despite my earlier misgivings. Options don't hurt anyone, quite the contrary.