general cleanup

[zevaverbach]

In addition to the items mentioned in the first (large) commit, I've also short-circuited a number of comparisons from 4-5 lines to one line and renamed unused values returned (mostly from external libraries) to _.

[karayaman]

Hi, thanks but cleanup is not that important. Check this issue if you want to contribute https://github.com/karayaman/Play-online-chess-with-real-chess-board/issues/23

[zevaverbach]

ah ok, no worries, will just work on my fork i guess