Add functions to emit and listen events of inspector

[gregogalante]

Sometimes we need to manage inspector functionalities from the outside. We can access with AFRAME.INSPECTOR but some operations can not be done with the Inspector class instance.

With this mode we can listen and emit events using AFRAME.INSPECTOR.

[vincentfretin]

There is already https://github.com/aframevr/aframe-inspector/blob/575c9106e26b41c714cc369b55c4db861315d7a0/src/index.js#L20 exposed We can just add this.off = Events.off; instead of using two other functions. Please don't include the dist in the PR.

[vincentfretin]

Ah and this.emit = Events.emit of course.

[gregogalante]

@vincentfretin this.emit = Events.emit is not existing. I create a new pull request

[vincentfretin]

Yeah this is what I meant, change your PR to expose off and emit.