Feature requests: Append dots, set dots by note/octave, get string/fret for note/octave.

[ava-gunn]

I'm using the library to build a fretboard/scale display with audio stream pitch detection to set a dot indicator to display the currently played note. I'm hoping to extend this to show the intervallic functions of the pitches surrounding the currently played note for the given chord scale. The idea being that a user could see: "I'm currently playing the 3rd of Mixolydian and the b7 is here".

Some features that I think would be highly useful are:

• Appending dots, or modifying dot styles without resetting or re-rendering the current scale display.
• Adding dots by note/octave (e.g. "A4") for the given tuning without having to calculate string/fret.
• Getting string/fret values for a given note/octave.