Migrate event system to use node events lib.

[dadiorchen]

We impletement the event system by simply call onXXX function parten, in this PR #20 #21 we try to use events lib to provide a solid and battle checked approach to implement event system, please migrate all other onXXX event to use
These listner is like onError, onLoad...

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[keyy123]

@dadiorchen If this issue is still open, I would like to handle it! 🙂

[dadiorchen]

@Mohmn I think you did something related to this?

[Mohmn]

yes , i was trying to provide a unsubscribing func