title: Use existing source code in another project/namespace
body: <p>I have two library projects within a single solution (in addition to other projects) which necessarily need to share certain classes but must remain separate for automatic-update reasons.</p>
  
  <p>For the classes that are shared, I would ideally like to use the same <code>class.cs</code> file in both libraries so that I don't have to consistently check that changes to the class are propagated through both libraries. </p>
  
  <p><strong>However</strong> the namespaces of the two libraries are different, and so the class-containing file in each library requires a different <code>namespace classlib {}</code> declaration.</p>
  
  <p>I am using a git repo, if there is a technique to do this through branch/merge operations.<br>
  Presently using VS2013.</p>
  
  <p>How can I achieve this?</p>
  
  <hr>
  
  <p>Example:</p>
  
  <p><code>library1.dll</code> </p>
  
  <pre><code>namespace library1
  {
      public class SharedClass
      {
          /// code must match SharedClass in libary2
      }
  }
  </code></pre>
  
  <p><code>library2.dll</code></p>
  
  <pre><code>namespace libary2
  {
      public class SharedClass
      {
          /// code must match SharedClass in library1
      }
  }
  </code></pre>