title: string sanitizer for filename
body: <p>I'm looking for a php function that will sanitize a string and make it ready to use for a filename. Anyone know of a handy one? </p>
  
  <p>( I could write one, but I'm worried that I'll overlook a character! )</p>
  
  <p>Edit: for saving files on a Windows NTFS filesystem. </p>