title: $(SolutionDir) MSBuild property incorrect when running Sandcastle Help File Builder via CMD
body: <p>When I run the Sandcastle Help File Builder project file (for example, <code>myproject.shfbproj</code>) using Windows CMD, I get an annoying issue: <code>$(SolutionDir)</code> has the same value as <code>$(ProjectDir)</code>, and this means that project documentation sources won't build correctly, because I'm adding custom targets which already use <code>$(SolutionDir)</code>.</p>
  
  <p>If I build the whole Sandcastle Help File Builder from Visual Studio it builds successfully.</p>
  
  <p>I'm using the following command (executed from the directory where the project is stored):</p>
  
  <pre><code>"C:\Program Files (x86)\MSBuild\14.0\Bin\MSBuild.exe" /p:Configuration=Development myproject.shfbproj
  </code></pre>
  
  <p>Is there a workaround for this?</p>