v2.0.0

Version 2.0.0 marks the completion of the effort to make Stockfish (and similar engines) work reasonably well.

We've come a long way since 1.0.0, when Nibbler needed to be manually configured with a text file...

Since then, we've gained - inter alia - Chess960 support, end-of-game detection, a legal moves display and movegen code, PGN and FEN compatibility improvements, a winrate graph, play versus engine and engine self-play, better engine configuration, full-game evaluation, custom pieces and custom backgrounds, various aesthetic improvements, a compliant UCI implementation, bugfixes, bugs, bugfixes, and finally Stockfish and A/B engine support.

P.S. Since many people complained - focus buttons are again (by default) shown when the engine is running.