Fire a new 'playerror' event when unable to play

[implicitdef]

When calling myHowlerObject.play(), the underlying call made to node.play() (https://github.com/goldfire/howler.js/blob/master/src/howler.core.js#L740) may fail under specific conditions.
My issue is that this failure is not detectable in any way by my code. Wrapping myHowlerObject.play() in a try/catch does not work, because the actual node.play() is probably called asynchronously. I've tried window.onerror too, without success.

Suggestion : wrap the node.play() in a try/catch in howler's code, and fire a new specific event like playerror if it fails, similar to the existing loaderror.

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My use case :
I'm trying to play a sound immediatly when the user arrives on a page (not triggedred by a user gesture). This is restricted on some mobile browsers, making the node.play() call fail. I would still like to have that autoplay if possible and be able to detect when it was blocked, and it that case display something else in the UI to onboard the user and invite him to play the sound. See discussion #609

[kane-mason]

I have created a fix that is working for me. You can view pull request here:

#721

[goldfire]

Closing due to inactivity. If this is still an issue, reply with more info and I'll reopen.