New feature: start and stop time for the play function

[katspaugh]

A new feature in 7.9.1! It's now possible to pass start and stop parameters to the play method:

wavesurfer.play(10) // will start playing at the 10s mark

wavesurfer.play(undefined, 20) // will start at the current position and end at 20s

wavesurfer.play(4, 7) // will play from 4s to 7s

Important

Please note that the end position is much more precise when using Web Audio playback (backend: 'WebAudio in the options). The default playback via an audio element is only accurate within +-16ms or so.

Docs: https://wavesurfer.xyz/docs/classes/wavesurfer.default#play
Implemented here: #4014