Scenario expansion

Mostly just adding stuff that I missed in the initial PR. 

-Allow forced/forbidden traits in scenarios: Done
-Limit start location choices based on scenario : In progress
-Various flags and starting conditions.
-Add more scenarios
I was debating between using the flag or not, and if you'd prefer to not have a flag that's doable.

As for some locations to be only attached to certain scenarios, It'd require quite a bit of extra finoodling, and honestly, starting locations aren't terribly OP/UP that i don't see the point in limiting them for your generic start.