Adding CSV example

[cspollard]

As discussed in #29 , a CSV-parsing example could be useful.

Looking at Text.Parser.JSON, I don't think what I have here is general enough to be in the main library (yet?).

I'm sure you'll have some comments and suggestions --- thanks in advance for that!

I've tested this on some example CSVs exported from google sheets. I don't know if there is a better "standard" out there, unfortunately.