title: EPPlus - shift rows up after DeleteRow
body: <p>h3110 3v3ry0n3, especially EPPlus team!</p>
  
  <p>I have an Excel template like this:</p>
  
  <pre><code> _______________________________
  |    Title 1    |    Title 2    |
  |_______________|_______________|
  | %Placeholder% | %Placeholder% |
  |_______________|_______________|
  | Special cell  | Special cell  |
  |_______________|_______________|
  </code></pre>
  
  <p><em>Special cell</em> - empty cell with some data validations and data lists.</p>
  
  <p>So, this template has double purpose:</p>
  
  <ul>
  <li>to be filled with data programmatically (replace <code>%placeholder%s</code>) or</li>
  <li>to be filled by hand (by selecting lists in <em>special cells</em>)</li>
  </ul>
  
  <p>In second case I invoke <code>sheet.DeleteRow(1)</code> and expect special row #3 to become row #2 (shift up), but this does not happen. So, the question is: <strong>is this a bug and I should post an issue or there is some workaround to force rows shift up?</strong></p>
  
  <p>Here're some thoughts. I guess, this could be caused by treating special cells as empty. May be, there is a way to copy data validations from row #3 to row #2? Also there is another similar question <a href="https://stackoverflow.com/questions/35297236/c-sharp-excelpackage-epplus-deleterow-does-not-change-sheet-dimension">C# ExcelPackage (EPPlus) DeleteRow does not change sheet dimension?</a> for more general case and it does not seem that deleted rows there are followed by empty lines.</p>