client-go: use the generated client library
Add variant protos

- also add new readsets.search name filter
Add support for retrieving data from NCBI

Note: not all NCBI fields are in exactly the right format (#23,#24, and
others) so the fields parameter must restrict the request to the fields
which parse well.

Java types are stricter than the other languages (like python) which is
why this isn’t as apparent in the other clients.
Merge pull request #36 from gkrasin/use-generated

client-go: use the generated client library