Track player time spent on alert continent

Unfortunately it's very hard to get an accurate figure of this. It can be done based off combat events (when X player dies or shoots someone) but it's difficult to indicate whether they are simply idle, or haven't kill or died in some time.

I'll have to work on this. It's a real shame that the game doesn't provide any kind of population metrics, but then again, that would be a rating of their performance.