• Chg : dispell() and getdata() now croak when an invalid signature is
  passed.
  
• Doc : More examples and a brand new synopsis.
  
• Fix : The signature is no longer stored in the mg_private member of
  the MAGIC struct. This fixes possible clashes with magics from
  other extensions.
  
• Fix : op info objects weren't blessed into the right class.
  
• Fix : Races when initializing the op names cache under threads.