title: How to get duration, as int milli's and float seconds from <chrono>?
body: <p>I'm trying to use chrono library for timers and durations.</p>
  
  <p>I want to be able to have a <code>Duration frameStart;</code> ( from app start )
  and a <code>Duration frameDelta;</code> ( time between frames )</p>
  
  <p>I need to be able to get the <code>frameDelta</code> duration as milliseconds and float seconds.</p>
  
  <p>How do you do this with the new c++11 <code>&lt;chrono&gt;</code> libraries?  I've been working on it and googling ( information is sparse ). The code is heavily templated and requires special casts and things, I can't figure out how to use this library correctly.</p>