Re: WIP patch: add (PRE|POST)PROCESSOR options to COPY

I wrote:
> > The biggest problem this patch has had from the very beginning is
> > overdesign, and this is more of the same.  Let's please just define the
> > feature as "popen, not fopen, the given string" and have done.  You can
> > put all the warning verbiage you want in the documentation.  (But note
> > that the server-side version would be superuser-only in any flavor of
> > the feature.)
> 
> Agreed.  I'll reimplement the feature using the PROGRAM keyword:
> 
> >     COPY TABLE FROM PROGRAM 'command line';
> >     COPY TABLE TO PROGRAM 'command line';

I've reimplemented the feature.  Attached is an updated version of the patch.

Todo:   * More documents   * More tests

Any comments are welcomed.

Thanks,

Best regards,
Etsuro Fujita