title: Django admin foreign key field filtering
body: <p>I have client model which has a foreign key field to a country model.</p>
  
  <p>So in Django admin, when I create a client and I select the country where this client belongs to. but the problem is the select list is too long(too many countries on this planet). Sometimes it takes just too long to get the one I need.</p>
  
  <p>So I wonder if there is other widget in djano admin that provides a select-input-combo widget.
  When I type in the input and it will filter out the right one for me to select.</p>
  
  <p>Hope you can understand what I need here.</p>