Update to Web Audio policy change

[bobbicodes]

...or, Resume AudioContext all the things.

A (sort of) recent change to the Chrome browser audio policy requires the Web Audio engine to be resumed once suspended if not explicitly started from within a user event.

We are currently dealing with this by resuming the AudioContext on certain events, if I recall correctly it is upon note entry.

This seems preferable to forcing the user to "Click here to begin" or the like, but this should be abstracted into a resume function that can be universally applied to other events that may have been overlooked. It will also make it more clear what it is doing.