Incorporate opensource timestretching algorithm

[rconstanzo]

Using something like Rubberband library (http://www.breakfastquay.com/rubberband/) for built in timestretching. (DiracLE is no longer available)

This thread on the c74 forum might provide some insight to potential problems:
https://cycling74.com/forums/some-utility-externals-rubberband-noteid-chordid/