janggi patch

[stjer]

Purpose

now it can support janggi variants

[QueensGambit]

Hello @stjer , thank you for your PR.
You introduced three jannggi variants in your PR: janggicasual, janggimodern, janggitraditional.
How do these variants differ from classical janggi?
If I see it correctly, you mainly updated css-files.

[ianfab]

Hello @stjer , thank you for your PR. You introduced three jannggi variants in your PR: janggicasual, janggimodern, janggitraditional. How do these variants differ from classical janggi? If I see it correctly, you mainly updated css-files.

To answer your question, the original reason I implemented these 4 different rulesets in Fairy-SF was that depending on the environment often slightly different rules are used for Janggi. It would be more natural to have a kind of configuration flag that indicates that, but since it impacts move generation the simplest was to treat them as different variants. They basically differ in two rules: whether bikjang (facing kings) and material counting (to get rid of draws) are used, so 2x2=4 variants. It is also briefly explained at https://github.com/fairy-stockfish/Fairy-Stockfish/wiki/FAQ#which-variant-should-i-use.

What is mainly relevant for competitive play are "janggi" (OTB rules) and "janggimodern" (common online rules), but the others are still in use in casual play and can also be somewhat relevant for analysis since some tournaments use different scoring for win by mate and win by material counting, while the engine treats them as equal.