* The required Qt version is now 4.6 (was 4.5).
* Redesigned and rewritten concurrency code. The rare deadlocks and segfaults between games (especially with high "-concurrency" values) should be gone now.
* Fix the command line parser in the Windows version. Now command line arguments following the executable name are parsed properly.
* Handle invalid draw claims from Xboard engines properly. Now an invalid draw claim from an engine in "Thinking" mode is recognized properly and does not result in a "Connection stalls" error.
* Check the legality of opening book moves. It's no longer possible to break the game with a faulty book file.
* Option "-srand" for setting the random seed for the book move selector manually.
* The "invertscores" option was renamed to "whitepov".
* Evaluation perspective ("whitepov") and init strings can now be configured with the engines.json config file.
* Option "-recover" for automatically recovering crashed or stalled engines instead of terminating the whole match.
* Display the ELO difference after the match has ended.
Source code (cutechess-lib + cutechess-gui + cutechess-cli) here
Mac OSX (Leopard or newer)