[cell format] Could we support 'Date' defined via Unix timestamp?
Would it be possible to support dates defined, in Unix fashion, as milliseconds since the 1970-01-01T00:00:00 epoch?
In this type of Date, the cell contents would be a number, e.g. 1544801404000, which would map, once the cells were formatted to the 'Date' format with the right interpretation pattern, to the date, in ISO 8601 format, 2018-12-14T15:30:04Z.
cheers, ~adrian