Implement Asian Xiangqi Notation (AXN)

[ugoproto]

The AXN is different from the PGN. It's a relative notation. An opening example:

Red Black C2=5 H8+7 red Cannon moves from file 2 to file 5, black Horse in file 8 advances and switches to file 7 H2+3 R9=8 red Horse in f2 advances and switches to f3, black chaRiot moves sideway from f9 to f8 R1=2 H2+3 red chaRiot in f1 moves sideway to f2, black Horse in f2 moves up and switches to f3

Is it possible to implement that notation in PyChess for Xiangqi and games related to Xiangqi?

A first step would be to adjust the boards: a Xiangqi board has a series of files, from 1 to 9, on the top (black players) and from 9 to 1 at the botton (red player); clockwise, it goes from 1 to 9 (top), and 1 to 9 again (bottom). That could be added without removing the algebraic notation.

A second step would be to record moves according to the AXN. I understand StockFish is based on PGN, but AXN would be added (not a replacement for PGN).

Here is an example from a Chinese software: http://xiangqibowl.org/?p=1568

[gbtami]

We plan to change to WXF notation as default, see https://github.com/gbtami/pychess-variants/issues/332

[gbtami]

WXF File format https://www.wxf-xiangqi.org/images/computer-xiangqi/chinese-chess-file-format.pdf

[gbtami]

Fixed via https://github.com/gbtami/pychess-variants/commit/a2ef7cf45580c3c7665b0ef4789178d2875017a6