Support removeEventListener inside event handler

Support the following (and similar) use-case:

```javascript
var object = new THREE.Object3D()
var doOnce = function() {
// do something
object.removeEventListener("foo",doOnce);
}
object.addEventListener("foo", doOnce);
```
Merge branch 'patch-2' of https://github.com/speigg/three.js into dev
Minor beautification.
Updated builds.