NAME
       GetCode -- return the true IDCMP message code

   SYNOPSIS
       code = GetCode( imsg )

       uword getcode( struct intuimessage * )

   FUNCTION
       Returns the true intuimessage code field. layout.gadget replaces
       the IDCMP_GADGETUP message with an IDCMP_IDCMPUPDATE. This function
       will return the "gadgetup code" from the IDCMPUPDATE taglist if it
       is found there, and otherwise the normal imsg->Code.

   INPUTS
       imsg -- a pointer to an intuimessage

   RESULTS
       The message's code field