let there be let

[Tobenna-KA]

Hi, I have made changes to this file most of which is var to let. I also tested the changes to make sure nothing breaks. I had to leave some declarations with var because of their global use.

I also noticed something I think is a mistake on line 3289 of the current version and line 3272 of this commit. The variable selectedNote is declared and assigned a value but never used. I think this variable is meant to be selectednote. Because if you look in the current version, within the same scope on line 3306, there is a passing of an argument selectednote to function piemenuPitches() which I believe should be the value defined for selecteNote. If you could please look at it.

There were also place I moved the variable declaration to a more global location within the same scope though, to allow the use of let.

[walterbender]

I think you are correct re selectednote vs selectedNote. I'l review tonight or tomorrow.