[ic] Removing session ID from the URL

[Grant]

> I also wanted to say that I'm going to try commenting out all Robot*
> directives and see how it goes.  mv_no_session and mv_no_count will be
> set to keep id and mv_pc out of the URI for everyone.
> 
> The downsides are the performance and storage hit of keeping track of
> sessions for robots, the exclusion of shoppers who don't accept
> session cookies, and the minor issue of browser page caching.

Replying to myself, I just realized I could eliminate the exclusion of
shoppers who don't accept session cookies by displaying some text on
an empty-cart shopping cart or checkout page that says something like:

Click here if you added items to your shopping cart that have disappeared.

That link could go to a page explaining that they should either turn
on session cookies or click here to enable shopping without them. 
That link could unset mv_no_session.  Is this feasible?

- Grant