Refactor with wavesurfer.js

[barrettk]

wavesurfer.js allows for manipulation of audio playback speed with pitch control, as well as an equalizer.

This is going to be a large effort (bigger than the last one)

[barrettk]

I found an R package that creates a widget using some of the available pluggins, but it's horribly bugged and is no longer maintained. You can do some pretty cool stuff with it though, and I think the htmlWidget will save me some time.

If I utilize wavesurfer.js's plotting capabilities it would A) replace a LOT of the work I did when hooking up the howler module, and B) be a significant effort. I cloned the R package wrapper, and may spend some time refactoring that package before pulling specific components I plan on using. It's tough to say how this PR will go, but at the moment I havent found any real alternatives for altering playback speed and using an equalizer via a web audio player.

After I fix the package a bit the first task will be getting the two js packages to communicate without any lag or glitching. My biggest fear is that I do a lot of work just to have it be a mess at the end. The upside is that this PR will likely be the largest effort. After which we can focus on adding multiple audio tracks, a decent test suite, UI redesigns, and getting ready for an official release.

Aside

At some point I want to revisit electron.js for packaging up package tarball with an installation of R to make an executable we could pass around more easily, but that is not trivial (I did something similar for my senior design project, but I wasnt able to bundle it with an installation of R to make it truly portable).