Anti-Kings

[PraseodymiumSpike]

https://www.chessvariants.com/diffobjective.dir/anti-king-chess.html

im specifically referring to the check mechanics of an antiking, the ability to self capture is probably in another issue

a player can have both a king and (possibly multiple) antiking(s)

[PraseodymiumSpike]

I guess I should provide a description better than a link. The only really unique thing this issue really asks for is the ability to make it so there is a piece that is considered to in check when on the board and not attacked but is not considered to be in check when attacked. An extension of #842 could take care of that antikings are not considered attacked by kings. #606 could take care of that antikings can't be legally captured. #608 could take care of that antikings only capture friendly pieces.