Added error checking to genbank

[Koeng101]

This adds error checking genbank to io.

There are a few things I need to figure out:

• Accession + Version + Definition formatting in build
• Locus comes up twice

I also need to figure out how to integrate concurrent reading (this will probably just be by modifying parse, even if that is a little annoying).

[Koeng101]

@TimothyStiles This code is ready.

I removed checksums, multi-genbank, and flat genbank parsing. These I think can be added later after we clean up the code a little bit.

[Koeng101]

Closed in favor of #244