[web-audio-api] Add an way to request mathematically correct oscillators (#244)

When using an OscillatorNode as an LFO, it can be useful to get rid of the ripples inherent to high frequency limiting to get precise modulation.

This issue is about designing an API to request mathematically correct oscillator, and define them using a mathematical definition (in terms of phase, waveform shape and peak amplitude). 

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Reply to this email directly or view it on GitHub:
https://github.com/WebAudio/web-audio-api/issues/244