Add wavetable oscillator

[brbrr]

Adds a bandlimited wavetable oscillator. The implementation is quite opinionated, and it would require some amount of refactoring to make it general enough to be used in multiple use cases.

It behaves similarly to Oscillator class, with the caveat that one needs to run Tables::Generate(); before processing the oscillator.

[stephenhensley]

ouu, very cool! Thanks for the contribution @brbrr

I should have some time to give this a look next week!

[beserge]

Sorry about working on top of you a bit, I think my repo was a bit out of sync and I re-fixed issues that had already been addressed. I'm going to squash and merge anyways, so it shouldn't be an issue.

If we can get it building again with the template change, that would be great!