Handle pitch invasion

[IBBoard]

Replay_2020-09-06_10-13-12.db has a pitch invasion in turn 8. Each player rolls a dice with modifiers to see whether they're knocked unconscious, but the game doesn't record this. We then end up with a blitz that we think is missing a dodge because we don't know that the player is down.

We might be able to do something with reading ahead to see when we expect dodges that don't appear (which indicates that the player isn't where we think they are) but that's going to be messy and patchy at best (players who a downed but then avoided by the opposition and never moved will never be flagged as down)