Additional output file formats

[dbhart]

While useful for storage, HDF files are not easy to work with. JSON files are somewhat easier to work with and the most compact format for storing all data, but still not terribly friendly for using data in other locations, such as in spreadsheets or visualization tools. The following are formats that ought to be easily specified as outputs:

1. CSV files - simple outputs in tabular form for the 1D by-time table and for single 2D tables.
2. Excel workbooks - output 1D summary in first sheet, specified 2D tables in additional sheets