Add proxy support

Adding support for proxies in the next CiviCRM version would be great!

I think proxy settings should be an option in CiviCRM/admin/setting
Using this approach, there is a patch for Drupal 6.x that will be part of Drupal 7:
http://drupal.org/node/7881
Maybe CiviCRM could use this Drupal setting or this Drupal approach.

I had a proxy problem with Google geocoding described in
http://forum.civicrm.org/index.php/topic,213.0.html
I added this line to civicrm\CRM\Utils\Geocode\google.php between lines 126 and 127:
$request->setProxy('my.proxy', 80);
and the Google geocoding and editing contacts problem disappear.

Maybe the same line should be added to civicrm\CRM\Core\Payment\google.php for other purposes.

(It would be good to add the possible proxy problem at:
http://wiki.civicrm.org/confluence/display/CRMDOC/Mapping+and+Geocoding)

Adding a proxy settings at the admin section will makes possible achieve a general and more elegant solution for this kind of problems.