title: What's the difference between find_package(MPI) and FindMPI?
body: <p>As stated in the <a href="https://cmake.org/cmake/help/v3.0/module/FindMPI.html" rel="nofollow noreferrer">documentation</a>  for CMake 3.0, <code>find_package(MPI)</code> and <code>FindMPI</code> seem to be interchangeable? But my questions are:</p>
  
  <ul>
  <li>What are the differences between these two? </li>
  <li>Is that also the case for the latest version? </li>
  <li>Also, does <code>FindMPI</code> provide anything similar to the option <code>REQUIRED</code> in <code>find_package()</code>?</li>
  </ul>