title: Finding all classes whose name matches a string
body: <p>I would like to find all ruby classes whose name matches a string(ignoring case).
  That means that the string should be a substring of the class name.<br>
  So when you search for 'stri' you should get the class <code>String</code> (among others) as a result.</p>
  
  <p>Do you know a convenient and not too inefficient way to do this?</p>