Add support for more time series formats

[pesap]

Some data files can have different format for specifying a time series. I think it would be nice to have some kind of logic to handle the different cases. Some of the proposed file formats (but not limited to) are the following:

• name, month, day, 1, 2, 3, 4, 5 (hours as columns)
• name, year, month, day, 1, 2, 3 (hours as columns)
• name, year, month, day, pattern, value (where pattern can be H1-5, H12-24)