title: How to Inject existing PDO object to doctrine entity manager
body: <p>I want to create a PHP package using doctrine entity manager.</p>
  
  <p>This package will be used in different projects in my company, and some projects are not using doctrine, but a PDO connection.</p>
  
  <p>I want to be able to instantiate a doctrine entity manager in my package with an existing stand-alone PDO object, because I don't want (and I just can't) to create another DB connection. I have to use the existing one.</p>
  
  <p>Is that a way to do that? Something like: </p>
  
  <p>$em = EntityManager::createWithPDOInstance($pdoObject);</p>
  
  <p>Thank you</p>