BLIDBGHAN
------------------------------------------------------------------------------

  Function : Set the Blinker debug handle

  Syntax   : nuValue = BLIDBGHAN([nuhandle])

  Return   : Previous debug Handle

  This function is used to get or set the Blinker overlay manager debug
  handle. It returns the previous debug handle, and takes as an optional
  parameter the new handle it should be set to.

  The handle defaults to 1 for the screen unless it is overridden at link
  time using the BLINKER DEBUG HANDLE command or at run time using the
  /DHn setting in the BLINKER environment variable.

  The new handle is not validated and may be either 1 to send output to
  the screen, 2 to send output to the standard error device, 4 to send
  output to the printer, or the DOS handle of a file opened by the program
  with a DOS open file call.

  This handle is used as the default output handle for a number of the
  other Blinker debugging and profiling functions, so may be set once at
  the start of the program rather than passing it as a parameter to each
  function individually.

  Example  :
  *  Get the current debug handle
  ? "The debug handle is currently", BLIDBGHAN()
  *  Set the current debug handle to the printer
  BLIDBGHAN(4)