Function:   CancelFile()

               When files have been submitted for printing (using
               SubmitFile()), the user can also cancel some files
               in the queue, these will then not be printed. Be
               carefull with this function, it is possible to
               cancel files that were not set by the program but
               any other DOS program, as PRINT can be used
               anywhere.

   Syntax:     CancelFile(<cFileMask>)

   Arguments:  <cFileMask> is the name of the file to cancel.
               wildcards are allowed.

   Returns:    Error code and 0 when no error. The code is a DOS
               error code.

   Usage:      CancelFile('*.MYP')  && delete My print files..