title: std::chrono & Boost.Units
body: <p>I'm working on a software design in which I'd like to leverage <code>Boost.Units</code>. Some of the units I'd like to use represent time, however, I'm inclined to use the C++11 <code>std::chrono</code> units for those since they're standard.</p>
  
  <p>I'm wondering if there's any clean integration between <code>Boost.Units</code> and <code>chrono</code> or whether I have to resort to writing my own converters and lose type safety by just copying scalar values between the types.</p>
  
  <p>Are there any best practices for this issue?</p>