[Csv] Moving _csv.c closer to PEP

[Kevin Altis]

> From: Dave Cole
>
> Skip> Speaking of doubling things, can the low-level partser support
> Skip> mulit-character quotechar or delimiter strings?  Recall I
> Skip> mentioned the previous client who didn't quote anything in their
> Skip> private file format and used ::: as the field separator.
>
> Currently the parser only handles single character quotechar,
> delimiter, and escapechar.
>
> I suspect that quotechar, delimiter, and escapechar of more than a
> single character might be stretching the bounds of what you could
> reasonably call a CSV parser.

Agreed! Double-byte Unicode characters would still be one character in case
we do have to do something special for unicode support.

ka