add a helper toString for PGNs in Pgn.Extra, and fix a bug that lead … (

#11)

* add a helper toString for PGNs in Pgn.Extra, and fix a bug that lead to partial results being classified as black's last move when white's last move was checkmate

* reword toString documentation, prepare for minor version bump release

version bump after error string docfix

bump minor version for fixes around legal movetext

Merge branch 'main' of github.com:shnewto/pgn into main

remove some unused deps from the package