title: Zend_Acl find all inherited roles
body: <p>I got chain of roles:</p>
  
  <pre><code>acl.roles.guest  = null
  acl.roles.member = "guest"
  acl.roles.admin  = "member"
  acl.roles.owner  = "admin"
  </code></pre>
  
  <p>in .....Controller/Action/Helper/Acl.php I have stored _acl object</p>
  
  <p>Is it a way to get list of my role and parents ?</p>
  
  <pre><code>$this-&gt;_acl-&gt;getParents ( 'admin' )
  </code></pre>
  
  <p>should return</p>
  
  <pre><code>admin, member, guest
  </code></pre>
  
  <p>as array, or string (eg comma delimited) </p>