Include WHO reference strains, vaccine strains, NCBI genotypes in trees

[kimandrews]

Description of proposed changes

This PR adds specific sequences and metadata to the measles trees, including WHO reference sequences, vaccine strains, and genotypes reported on NCBI, through the following steps:

• Dropping GenBank accession version number (resolves #24)
• Force-include vaccine strains in N450 and genome trees (follows up on https://github.com/nextstrain/measles/pull/23)
• Add WHO genotype reference strains to N450 tree (these sequences are too short to include in the genome tree)
• Use a custom script to parse genotypes from the virus-name field of the NDJSON record from NCBI (addresses https://github.com/nextstrain/measles/issues/16)
• Include genotype coloring on N450 and genome trees

Related issue(s)

https://github.com/nextstrain/measles/pull/23

24

https://github.com/nextstrain/pathogen-repo-guide/pull/40 https://github.com/nextstrain/measles/issues/16

Checklist

• [ ] Checks pass