[Feature request] Improve tank logic

[Tiagoquix]

Hello there.

One of the things I noticed while playing SZF is that tanks spawn at a very low frequency, even when the server is full (32 players). Tanks rarely spawn, and when they do, there is only one per game, even though the zombies are losing overwhelmingly.

I would like to suggest that somehow the logic of choosing a tank was improved so that there were more per game. You could even do something like having at least 1 tank per game when the number of players exceeds X players, in order to always guarantee a certain level of difficulty.

Thank you for your attention.