title: iTextSharp : merge the last column (Colspan)
body: <p>I have a table, this table has 3 columns. In each column, there is a table like the picture. 
  I did a method to generate table, this method receive a list in argument and loop on it to 
  addCell to the table</p>
  
  <p>I'd like for a line has a instead of 5 columns ... 1 + 1 (colspan of 4). When I do a colspan
  the 4 first are merged, I'd like merged the 4 last and keep the first.</p>
  
  <p>How can I do this ?</p>
  
  <p>Thanks,</p>
  
  <p><img src="https://i.stack.imgur.com/E9bPV.png" alt="enter image description here">
  <img src="https://i.stack.imgur.com/QVWNL.png" alt="enter image description here"></p>