title: How to convert a non-core csproj to VS2017 format
body: <p>I have two projects in VS2015 </p>
  
  <ol>
  <li>One .NET Core (project.json, xproj)</li>
  <li>One regular .NET csproj </li>
  </ol>
  
  <p>When I open project 1 with VS2017, it nicely migrates to the new csproj format. </p>
  
  <p>Project 2 works in VS2017, but I like to convert/migrate/update this csproj to the new project file format to benefit from the new csproj features (multi target, no large file list, readable csproj, NuSpec info in csproj etc)</p>
  
  <p>How could I do that? I cannot find an option in VS2017 for that.</p>
  
  <p>Using: VS2017 RTM</p>