Features
* export: Add support for custom legend and color scale specifications in Auspice config files [727][] (jameshadfield)
* utils: Add support for compressed strain name files (e.g., "include.txt.gz") [730][] (benjaminotter)
* filter: Rewrite internal logic to use pandas DataFrames ([743][]), define filters and subsampling logic as individual functions ([745][] and [746][]), and iterate through chunks of metadata instead of loading all records into memory at once ([750][]) (tsibley, huddlej)
Bug Fixes
* distance: Change numeric type of distance output to float [729][] (benjaminotter)
* filter: Disable probabilistic sampling when users provide `--sequences-per-group` [737][] (benjaminotter)
* export: Provide correct missing file error messages for metadata and node data JSON inputs [752][] (benjaminotter)
[727]: https://github.com/nextstrain/augur/pull/727
[729]: https://github.com/nextstrain/augur/pull/729
[730]: https://github.com/nextstrain/augur/pull/730
[737]: https://github.com/nextstrain/augur/pull/737
[743]: https://github.com/nextstrain/augur/pull/743
[745]: https://github.com/nextstrain/augur/pull/745
[746]: https://github.com/nextstrain/augur/pull/746
[750]: https://github.com/nextstrain/augur/pull/750
[752]: https://github.com/nextstrain/augur/pull/752