This is primarily a relatively small bugfix release. These are the major user-visible changes in 2.1:
- A number of crashes in odd situations were fixed (such as analyzing games with komi values like 650, or handling invalid server messages).
- It is now possible to copy/paste positions in Edit mode.
- The batch analysis dialog has a new button to enqueue an entire directory of SGF files.
- Engine games now allow board sizes up to 52.