title: Marionette difference between command/comply, listento/trigger, request/reply
body: <p>I'm working on some legacy code and have come across 3 similar constructs for triggering events</p>
  
  <ol>
  <li>command/comply 
  
  <ul>
  <li>trigger: <code>.command('update:mySetting', newSetting);</code></li>
  <li>handle: <code>.comply('update:mySetting', myCallback);</code></li>
  </ul></li>
  <li>listento/trigger
  
  <ul>
  <li>trigger: <code>.trigger('change');</code></li>
  <li>handle: <code>.listenTo(myModel, 'change', myCallback);</code></li>
  </ul></li>
  <li>request/reply
  
  <ul>
  <li>trigger: <code>.request('change');</code></li>
  <li>handle: <code>.reply('change', myCallback);</code></li>
  </ul></li>
  </ol>
  
  <p>What is the difference between these events and when should I use each of them?</p>
  
  <p>Thanks</p>
  
  <p>Note: I'm not sure if all of them come from marionette</p>