0.6.0

Breaks:

• An archive, spill or saved result written by 0.5.0 is refused: the layout is 3.
• catalog.parquet has no dim_position.
• owned.parquet is at answer/windows/, and only with keep_windows=True.

The pull requests since 0.5.0:

• fix(data): a datetime label is held in microseconds whatever unit it arrives in (#1839)
• feat(archive): an archive writes every column as a type that parquet readers agree on (#1835)
• fix(archive): an archive's catalog describes each file as it is written, and kept windows have a catalog of their own (#1838)
• fix(sweep): a sweep over a datetime axis in nanoseconds or milliseconds solves rather than crashing in its first slice (#1848)