GoodBoyDigital/pixi.js — pull request #578 by anissen (2014-02-13 22:24:18+00:00)
Title: Mouse wheel handling in InteractionManager

Mouse wheel (i.e. scroll) handling in Pixi.

I implemented it like `onMouseMove`, that is, with no hit-detection on items in the Stage.

The crazy mouse wheel normalization code is rewritten from http://stackoverflow.com/a/13650579

**Pixi power!** :facepunch: