title: Difference between boost::chrono::time_point<> and boost::chrono::steady_clock::time_point
body: <p>What is the difference between <code>boost::chrono::steady_clock::time_point</code> and <code>boost::chrono::time_point&lt;boost::chrono::steady_clock,Duration&gt;</code>, and why can't they be converted between each other?</p>
  
  <p>It seems extremely redundant.</p>