finalize version 3 revisions

Version 3 removes all 'hardcoded' metadata values from the XML templates, and puts all metadata into either the script itself or drawn by the script from the metadata spreadsheets.

In addition, version 3 allows for the inclusion of various subject elements, allows calculates durations using time deltas and allows time to be expressed in ISO format or in minutes, and names many of the expected spreadsheet columns more intuitively and correctly, based on input from DCMR.