title: Flex FileReference prohibited characters
body: <p>The use of FileReference has a constraint on valid characters.<br>
  <code>Error: Error #2087: The FileReference.download() file name contains prohibited characters.</code><br>
  This is fine since I guess the restriction comes from the underlying file system anyway<br>
  <br>
  <strong>Is there such a things as a generic way to trim / replace all prohibited characters?</strong><br>
  <br>
  For clarity I am after something like:<br>
  <code>var dirty:String = "Eat this !@##$%%^&amp;&amp;*()\/";.txt</code><br>
  <code>var clean:String = dirty.replaceAllProhibitedCharacters();</code><br>
  <br>
  I am not looking for OS specific regular expressions, but a cross platform solution.</p>