GNU Backgammon support and quick tagging

I've just deployed a new version of backgammondb.com. Main new feature: BackgammonDB is no longer XG-only. There's also a new quick-tag, improvements to move lists and note taking, plus a bunch of bug fixes and quality-of-life improvements.

GNU Backgammon import

You can now import .sgf match files. This is the standard game format used by GNU Backgammon. Old Jellyfish files should also work, though this is untested. Matches parse to the same shape as XG matches, everything should work just like before: error breakdowns, position tagging, search, quizzes, sharing etc.

A few details:

• GNU's cmarks on candidate moves become stars on the action itself.
• The match header shows which engine analyzed the match.
• Tutor mode is supported, but the only information in the file is the result after any accepted tutor decisions. The file does not encode your corrected mistakes.

Note that BackgammonDB still follows the XG standard for different bandings. For example, what's considered an error, blunder, or lucky (joker) roll. These can all be customized in settings if you want to follow GNU (or any other) format.

Quick tagging and note taking improvements

This is my fav new feature: You can now tag with just keypresses without opening the notes side sheet. Press T on any position to open a tag popup, then press the first letter of a tag to apply it. Two keypresses to tag a position — T then R applies "reference-position" (assuming you have that tag set up).

I've also made other fixes to note taking. I've simplified the note taking box, which fixed a host of key navigation issues. I fixed a bug with stars and notes not working in position walkthrough. Taking a note no longer "auto-stars" a position.

Improvements to the move list

Jokers/anti-jokers show in the move list. Lucky and unlucky rolls can be flagged in the move list, with a setting to turn it on. It is off by default, because to me it's just noise; but XG has this, and I know luck is something lots of people track, so I've added it.

Note: I have deviated in an important way here: BGDB shows luck from the perspective of the active player of that move, not the "hero" of the match. I have always found XG's system confusing. Thinking that an opponent's lucky move is our bad luck is just an odd perspective I've never got my head around. But if people want the XG way, I can add a setting.

The icon is always a four-leaf clover: Green for joker, red for anti-joker. This threshold can also be configured in settings.

There's also stars and notes in the move list. I've also added an icon for whether you have annotated, tagged or starred a position. It works in that hierarchy: A "note" will override a tag or a star, showing the highest by precedence. Hover over a note or tag to see your note in a tooltip. Click to open the notes sheet and edit.

Other improvements

• Resignation decisions now fully supported. Correct resignations display properly, and resignation decisions can now be shared and quizzed — is it right to resign a single game here? Should you accept a gammon resignation? Test your friends, they'll hate you for it.
• "Any annotation" filter. The positions page can now filter to anything starred, tagged, or noted in one click, and shows the total count of positions in your database.

Fixes and speedups

• Stepping through a walkthrough with hundreds of positions is much faster.
• Fixed move-list filtering display issues.
• Fixed sheets overlapping sheets on match review, and notes being lost when switching sheets via hotkey.
• Numbers are now formatted with thousand separators, the import modal closes itself after a successful import, and assorted navbar glitches are gone.