PURPOSE: (one line)
    General purpose image display (front-end for itool\_\_define).
    This procedure simplifies the use of the object-oriented itool GUI,
 (the 'itool' object class) by acting as a "front end" procedure which may
 be called from the IDL command prompt.
    By default, this procedure runs the itool GUI in non-blocked mode.
 There is a side-effect from running in non-blocked mode: only a copy of
 the input argument is passed to the itool GUI. Hence, any changes to the
 image within the itool GUI will be lost. Currently, the pixel editor in
 the itool GUI is the only mechanism for modifying the image. If the user
 wishes to retrieve a modified image argument, the itool GUI must be
 launched in blocked mode. Setting the BLOCK keyword to this procedure
 will run the itool GUI in blocked mode. Upon closing the GUI, this
 procedure will exit to the IDL command prompt and the input image
 argument will be available. Any changes made to the image while running the
 itool GUI in blocked mode will be reflected in the image argument.


    image : The image array.

  BLOCK          : If set, forces the itool GUI to run in blocked mode.
                   Otherwise, the itool GUI is launched in non-blocked mode.
                   Running the itool GUI in blocked mode allows the itool GUI
                   to modify this procedure's incoming image argument.
                   Otherwise, the itool GUI works with a separate copy of
                   the image, in which case any changes made within the
                   itool GUI will be lost.
  FVISIBLE       : Size of the full-view window (128 pixels).
  PHOTPARMFILE   : Optional photometry parameters file.
  TMPLFILE       : Optional Photometry template file.
  SCLMIN         : Stretch range minimum.
  SCLMAX         : Stretch range maximum.
  WXVISIBLE      : Creates work window with explicit x-size (500).
  WYVISIBLE      : Creates work window with explicit y-size (500).
  WZOOMFACT      : Ceiling for work-view zoom factor (unlimited).
  ZVISIBLE       : Size of the zoom window (128 pixels).






    Written by Doug Loucks, Lowell Observatory, July 29, 1994. This is a small
 'front-end' for the new compound widget version of itool (cw_itool).

  94/09/27 - Marc W. Buie, Lowell Observatory.  Modified exit on itool_event
               to eliminate crash on exit if photometry or template parms
               were changed.

  2004/04/15 - Doug Loucks, Consultant for Lowell Observatory. Overhauled to
               work with the new object-oriented version of itool
  2004/05/15 - DWL, Added the BLOCK keyword. See description for details.
  2006/03/15 - DWL, Minor modifications to reflect changes to the itool GUI.
                 Those changes involved the single argument to
                 the itool GUI. Previously, it was a pointer to a structure.
                 Now, it is an object reference of the 'itoolimage' class.
                 This new class eliminates the need for the procedure
                 itool_init. Instead, initialization and cleanup are
                 handled by the init and cleanup methods defined for
                 the 'itoolimage' object class.
                 Also, there is a new keyword to the 'realize' method of
                 the 'itool' object class. That keyword is ARG_CLEANUP.
                 If set, the itool GUI will handle the destruction of the
                 object passed as its single argument. Otherwise, it is the
                 caller's responsibility to destroy the object of
                 the 'itoolimage' class. This procedure sets the ARG_CLEANUP
                 keyword, whenever the itool GUI is launched in non-blocked