Add heatmap from pre-analyzed moves

[kevinsung]

Part of #487 .

This lets Sabaki recognize the non-standard SGF properties VISITS, WINRATE, and SCORELEAD in order to draw a heatmap even with no engine analysis session running. Values from a running engine analysis session would override the values from the SGF.

I assumed the following definitions for these properties, but I can change them:

• VISITS: number of visits
• WINRATE: probability of black winning as a float in [0, 1]
• SCORELEAD: number of points black is winning by

The diff is deceptively large because I indented an existing block by an additional level.

I have written a script that uses KataGo to add these properties to an SGF file: https://github.com/kevinsung/katago-analyze-sgf.

Screenshot:

[yishn]

I don't like the non-standard SGF properties. Is anyone else using these? 🤔 I did intend for the heat map to be a fleeting (temporary) board layer as opposed to persisted in the SGF file. But more people do full-game analysis beforehand and want to look at the results. Maybe sync with @pnprog.

[kevinsung]

Yeah, for better or worse, using non-standard SGF properties is the most straightforward way to support full-game analysis. I did reach out to @pnprog at #487 but he hasn't responded. I would also love to know if other tools use similar non-standard properties; I couldn't find any besides @pnprog's Go Review Partner.