Missing forced checkmate in dead positions

[krestenlaust]

Impossible checkmates in dead positions

[krestenlaust]

It seems pretty difficult to detect dead positions (https://chessily.com/glossary/dead-position/), but some basic scenarios, like two kings and a horse, or only two kings should be pretty easy to implement. But it might be a bit difficult to do and keep the same performance-level for the bot

[krestenlaust]

@danielweper if you're bored. Have you got any ideas for how to detect a dead position?