clarifying _toUnits and _fromUnits
clarifying _toUnits and _fromUnits

Tonejs/Tone.js,TONEnoTONE/Tone.js,BlokDust/Tone.js,TONEnoTONE/Tone.js,Tonejs/Tone.js,BlokDust/Tone.js,lukephills/Tone.js,lukephills/Tone.js