title: Pyramid: extend query string for every URL constructed by route_url
body: <p>I'm using the Webframework Pyramid and URL Dispatch where I defined a lot of Routes like</p>
  
  <pre><code>config.add_route('login', '/login')
  config.add_route('logout', '/logout')
  </code></pre>
  
  <p>Now I want to append something to the query string, such that URLs that are constructed by </p>
  
  <pre><code>request.route_url('login')
  </code></pre>
  
  <p>are actually</p>
  
  <pre><code>/login?foo=bar
  </code></pre>
  
  <p>This should be done on a project basis to avoid writing</p>
  
  <pre><code>request.route_url('login', _query={'foo': 'bar'})
  </code></pre>
  
  <p>everytime I want to construct an URL.</p>
  
  <p>What is the right place to do this? Should I somehow inherit from the pyramid.request class and overwrite the route_url method? Is there an event or hook that I can use?</p>