title: recursive tree evaluation of excel formula
body: <p>I have a top cell which contains a formula referring to other cells.
  Those cells contain formulas referring to other cells.</p>
  
  <p>I would like to evaluate the top cell while replacing in the whole evaluation tree every occurrence of a cell, say A4, by another cell, say A5.</p>
  
  <p>I know you can navigate the tree of dependants, but can you evaluate the formula after performing a replacement ?</p>