Combine hgnc and ensembl into single tsv extraction

[amc-corey-cox]

• rewrite each extraction to use the new tool
• remove all the dead code

We now have a single tool for extracting form .tsv with some helper functions. This should now be fairly robust as it handles several use cases. Please let me know if you see any issues.

I'm sorry this looks like such a big patch. This required a fair amount of moving things around because there is an optimal order for operations I needed to switch to. Also, we get a small performance boost due to only reading the hgnc file one time instead of 3.