Features
* align: New sequences can now be added to an existing alignment. [422][]
* align: Multiple sequence files can be provided as input. [422][]
* align: Extra debugging files such as `*.pre_aligner.fasta` and
`*.post_aligner.fasta` are no longer produced by default. To request them,
pass the `--debug` flag. [422][]
* align: De-duplicate input sequences, with a warning. [422][]
* export v2: Add support for the `branch_label` property in `display_defaults`,
which was recently added to Auspice. [445][]
Bug fixes
* align: Exits with an error earlier if arguments are invalid instead of only
printing a warning. [422][]
* align: Performs more error checking and clarifies the help and error
messages. [422][]
* export v2: Traits which are filters but not colorings are now exported as
well, instead of being left out. [442][]
* export v2: Exits non-zero when validation fails, instead of masking errors.
[441][]
* validate: In order to improve clarity, messages now include the filenames
involved and distinguish between schema validation and internal consistency
checks. [441][]
[422]: https://github.com/nextstrain/augur/pull/422
[441]: https://github.com/nextstrain/augur/pull/441
[442]: https://github.com/nextstrain/augur/pull/442
[445]: https://github.com/nextstrain/augur/pull/445