Add goToLive method

[avelad]

Add goToLive method to the Player. This new method is very useful in live streams.

[michellezhuogg]

Thank you for your contribution!

[shaka-bot]

All tests passed!

[joeyparrish]

If you want this to show up in production, then revise this to "alwaysWarn". warning() will be removed in production builds.

If you're happy with this only showing up in debug, then it's fine as-is.

[avelad]

I don't have a preference, I do what you prefer...

[joeyparrish]

It's fine with me. Just wanted to make sure you knew you had options.

[defnull]

I notices that with bufferingGoal: 4 (and the default for rebufferingGoal, playing dash with 2s segments) the player will wait (buffer) for 4 seconds after calling this method. Is that intended? The time_and_duration widget will also count backwards to -0:04 before playback continues. Maybe the bufferingGoal (or the manifests minBufferTime) should be subtracted from the seek point?

Edit: I never managed to get the time_and_duration widget to display 'Live' for my live stream. Maybe there is something wrong/odd with the DASH manifests generated by ffmpeg. Or seekRange().end points to the actual live edge, but does not take mandatory buffering goals into account? Not sure.