-d / -dt options for parsing columns as dates

[simonw]

SQLite prefers yyyy-mm-dd style dates - it can then sort them easily plus it has date functions which know how to work with them.

csvs-to-sqlite should have arguments that let the user specify columns that are known to be dates (or datetimes). It can then parse those dates and output them in the preferred format.

https://github.com/scrapinghub/dateparser looks like a good library for this: it can handle date parsing across many different languages, making it a potentially better fit than http://dateutil.readthedocs.io/en/stable/parser.html