Generate click track as buffer

[ericyd]

Rather than creating an audio buffer for each click, generate a full click track as an audio buffer for each loop, and just play that loop.

There is apparently a long-standing bug regarding pausing that I didn't realize, and it comes to light in an ugly way with this change: suspending and resuming the audioContext does not align with the clock 😱. That is, when the clock is stopped and started again, it will just resume clicking immediately when the button is clicked. However, the audio buffer will be stopped from mid-beat, which is hard to get right inside the clock.

Need to think more on this. It kind of indicates yet again that a setInterval is not the right way to schedule things -- probably should be using AudioContext. Need to think more on this before merging