Project files store timestamps in different formats

[zfi]

It appears that project files from different eras are storing the project created and modified dates as either an epoch value (number of seconds since January 1, 1970) : 1588609408691 or as a full text string in the format of: Thu Apr 09 2020 20:48:32 GMT-0700 (Pacific Daylight Time).

These dates should be stored as epoch dates, which are more compact. The process of loading existing projects which contain the full text date should convert them to epoch date format when stored in the Project object.