on antag odds

[Arborinus]

I considered a probability system for antag roles based on the player's history of antag selection, granting a higher weight for future selection the longer it's been since any selection at all.

Thoughts?

How would this affect late-joining antags? They occur even if you have all antags turned off in preferences (pls fix). Seeing how that by itself would cause a long break between selections it would select you for late join a lot.