title: PHP documentation generator with ability to cross-reference between versions
body: <p>I'm looking for a PHP documentation generator (like PHPDocumentor, Sami etc.) with the following features:</p>
  
  <ul>
  <li>PHPdoc support</li>
  <li>can generate documentation for undocumented functions</li>
  <li>can cross-reference with source code</li>
  <li>can cross-reference between versions on the file/class level (e.g. when I have 1.0, 1.1 and 1.2 branches, and I'm looking at the 1.0 version of some class, it will have links to the 1.1 and 1.2 versions of the same class, but only if it exists in those branches). Big plus if it can generate some sort of cross-ref table between classes and versions (or functions and versions).</li>
  </ul>
  
  <p>Is there a tool that can do this (or can be customized into doing this with reasonable amount of work)?</p>