[minor] Linux xdg user folder standard

[pirate486743186]

This is minor, the game still runs fine.

Normally, the config should go in $XDG_CONFIG_HOME/taisei, if XDG_CONFIG_HOME is not set, then in .config/taisei . A lot of projects hate moving these files.

log.txt should go in $XDG_CACHE_HOME/taisei, if $XDG_CACHE_HOME is not set, then in .cache/taisei. This can easily be moved. You could ass well rename it to taisei.log.

For .local/share/taisei, $XDG_DATA_HOME should normally be checked first if it exist. I don't know if this is done already.

the xdg standard
https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html

[chayleaf]

XDG_STATE_HOME should be used for logs