work on event emitter class

[gdeb]

EventEmitter should have:

on method (exactly the same as addListener) removeListener once method (like node.js)

global listener (all events) removegloballistener?

Or: using EventEmitter from node???

[gdeb]

using node EventEmitter adds about 10k of uglified js code at the end. Is it worth it?

in any case, a custom EventEmitter should be as compatible with node EventEmitter as possible