bug#3166: browse-url: browse-url-firefox url encoding

[Chong Yidong]

> For the _encoded_ url the displayed page in FF 3.0.10 is not the page
> displayed when copying the _unencoded_ url directly in the browser
> adress bar.
>
> I tested this also by directly copying the urls into Opera 9.64 AND even
> encoding the url with `browse-url-firefox' from current CVS emacs.
>
> Example:
>
> http://www.z-ac.de/component/option,com_eventlist/Itemid,23/func,details/did,761/
> =>
> http://www.z-ac.de/component/option%2ccom_eventlist/Itemid%2c23/func%2cdetails/did%2c761/

Thanks, I've checked in a change that removes the encoding of commas.
(It's possible the entire encoding process is bogus, but I left the rest
in place for now.)