title: How to install OpenCV 3.0 with nonfree module?
body: <p>I've tried a few times but most guides out there only tell you how to install it AFTER you've built OpenCV. I've had 2 unsuccessful attempts doing it this way and it's been a lot of work to do it this way, so </p>
  
  <ol>
  <li>I'd appreciate (and other people reading later might appreciate) basic instructions on how to install it (assuming dependencies are already there). </li>
  <li>Is it best to use git or build it yourself? </li>
  <li>What instructions must cmake be run with? </li>
  <li>Is it better to just build an old version (say 2.4.9) since version 3 is unreliable so far?</li>
  </ol>