v2.2.1

Full Changelog: v2.1.5...v2.2.1

I've released v2.2.1 with all the fixes and changes Bart recommended. Thanks for testing, it was very helpful. Please give it a try. Added timeseal v1 in the last release but here are the current changes.

Engine play
Repetition fix: the engine used to be sent only the current position, so it couldn't see earlier positions and would shuffle into threefold-repetition draws. It now gets the full move history every turn. Takebacks and joining a game midway are handled.
Pondering: with "Ponder": "true", the engine thinks on the opponent's time about the reply it expects. If the opponent plays that move, the engine keeps what it found; if not, it stops and searches the real position.
Engine book detection: moves from the engine's own book (OwnBook) are now recognized, and the GUI and PGN mark them as book moves.

Saved games (SavePGN)
Clock times: every move gets the clock left after it ([%clk 0:04:58]), which Lichess, ChessBase and SCID show as a clock.
Engine notes: the bot's moves get score/depth and the time taken, e.g. {+0.35/18 2.1s}, or {book} for book moves.

GUI
Book loading: the status bar shows the opening book loading, with its size and how long the load took.
Console: bare fics% prompt lines are hidden, and every line gets a timestamp to the millisecond.
Score chart: now uses the bot's side, matching the engine panel, with a "+ = us ahead" caption.
Resign button: appears during a game and asks for confirmation before resigning.
Book moves: highlighted on the light-square blue in the Moves panel.
Fullscreen: pressing F outside the input line toggles it.
WSL2: the window falls back to X11 when the Wayland connection is missing, and if the window can't open at all, it says why in the terminal instead of exiting silently.

Terminal
FICS style 1 board: black pieces marked *, the board drawn from the bot's side, and the move number, last move, clocks and strengths down the right side. The plain and colored versions both use it.