Use VBML codes for colored / blank / filled characters.

[DanielBaulig]

The Vestaboard API now supports VBML (Vestaboard Markup Language), which among other things supports a better way to encode Vestaboard special characters (like the color squares) into plain text.

The Vestaboard integrationhad provided it's own custom way to encode them using \xc1 to (now) \xc9 characters. But those, when rendered as regular strings, are valid, but different unicode chracters, meaning when actually displaying them in text they don't look anything like what you expect and are hard to read and understand.

VBML supports curly-braced tokens to encode any Vestaboard character, e.g. {63} for red or {0} for blank. I will look into replacing the current encoding with this encoding for better readability and compatibility with the actual Vestaboard APIs.