CSV syntax auto-detection

[sagebind]

Detect CSV delimiters, escape chars, and value delimiters automatically using a heuristic analysis.

Here's some code in cpython that auto-detects a CSV format for inspiration:

https://github.com/python/cpython/blob/e13a4151e45f74fc4efa1a928f9f6f700e89a5b4/Lib/csv.py