Basic line detection

![hz_handdrawn_circuit](https://cloud.githubusercontent.com/assets/5607966/2612289/a64ec810-bbbe-11e3-938c-a7f1997a43ea.jpg)
![vt_hz_handdrawn_circuit](https://cloud.githubusercontent.com/assets/5607966/2612290/a64f80fc-bbbe-11e3-8acf-86c131b57a83.jpg)