Can't use with visual impairment

[kujiu]

ShinKGS have several major accessibility issues for blind users. For low vision, we need at least:

• dark mode (see #231 ) to avoid high luminosity pain;
• board themes (see #68 ) with the ability to choose our colours for high contrast;
• better contrast in general. For all form of visual impairment please:
• set a good label on each button, specially on goban (like "White H17"), screen readers say only "button" now;
• better keyboard navigation in goban;
• correct ARIA references (a lot are broken);
• create alerts with all needed informations (like "White plays H17" or "5 minutes left");
• testing often with blind users.

I'm not the only one legally blind player and we open new go clubs for visual impairments.