title: Make a NuGet package copy content files to the output folder of parent project during build
body: <p>I'm trying to compose a NuGet package containing my assembly and it's required data files. </p>
  
  <p>What I would like to happen is when the parent project referencing my NuGet package is built, the data files from my package are copied to the output directory of the parent project. </p>
  
  <p>This sounds straight forward but if I flag the data files as <em>content</em> in my package project they're just added to the parent project on install but not automatically copied on build.</p>
  
  <p>I would like to do this with a custom .targets file in my package if possible.</p>