Imran Haque

@gulopine The meat here is in 994d031, which fixes up the `__metaclass__` usage and inheritance to make this module compatible with Python 2. Builds on #1.

@gulopine The real changes here follow 994d031 (the first two commits are just #1 and #3). This PR makes the following changes beyond those two: 1. Add `UnicodeColumn`: it's like...

In addition to the current "All", "Missense+LoF", and "LoF" filters, it would be great to have another filter for "ClinVar pathogenic". There are some semantic issues around ClinVar's classifications, but...