New Cone test

![screenshot from 2014-04-28 20 16 42](https://cloud.githubusercontent.com/assets/2906365/2824531/9e89a1b2-cf33-11e3-9f66-6e261062bdb8.png)
So, here is a new test which demonstrates the problem, which, as I stated in [#17](https://github.com/jdan/isomer/pull/17#issuecomment-41620325), is not in my code.