craftyjs/Crafty — pull request #816 by blainesch (2014-08-16 21:08:54+00:00)
Title: Add ability to see if two polygons overlap.

![poly_overlap](https://cloud.githubusercontent.com/assets/769039/3943137/75425e8c-2589-11e4-9551-c1e1a3ce0896.png)