next: Support use different color to indicate move blunder in variation

[zsalch]

Base on #412
Closes #389

Color node:

With comment node:

1. Config:
   "blunder-winrate-thresholds": [-30,-20,-10,-5,5,10],
   "blunder-node-colors":[[255,0,0],[0,255,0],[0,0,255],[255,255,0],[0,255,255],[255,0,255]],
   "comment-node-color":[0,0,255,255],

2. Ctrl+T for toggle the node color with the comment

3. Press ‘Y' for switch node color display

   default (show color) -> only black color -> only white color

[featurecat]

LGTM

[featurecat]

By the way, you forgot to add the three config values to the config file. So I had to add them to get it to work. I fixed it. You should try deleting the config file as a test before making a PR, to see if a new feature still works.

[featurecat]

Actually apparently the node color is part of the theme. I'm not sure how I got it to work but it no longer works as of now. It's not part of the default theme which is problematic.

[zsalch]

You are right. Only these three options have no default value. I missed them.