[ts.parse] implement _guess_ts_info

If no manifold has been provided, this creates a dict with all the
manifold fields.
It's tested with a nice dataset, harsh & real life tests to come.
[tst/data] fix name in timestream manifold
[ts.parse.validate] add file ext->img type mapping

Also a date format constant
[ts.util.imgmeta] fix up docstrings & logging

There were some mixed use of {0} and {} in format strings, and some
copy-paste errors in docstrings
Merge branch 'dev' into upstream

Pull in some misc recent fixes