ListTree widget

HISTORY:

---Version 0.1:
15 May 95	rwmcm Created
16 May 95	displays a simple (no branching) list
17 May 95	does branches without lines
18 May 95	added the line drawing
19 May 95	added bitmaps
22 May 95	changed line drawing, added Xpm support
23 May 95	convenience functions for shifting children around
24 May 95	working on test program
25 May 95	fixed bug that reparented children incorectly
26 May 95	adding resource specification for pixmaps
27 May 95	Creating file selector demo program
30 May 95	Turned file selector demo into a widget
 1 Jun 95	Programs mostly finished.  Waiting for documentation
 6 Jun 95	trouble with a few buglets
 9 Jun 95	finally found memory allocation bug in MakeCallbackStruct
19 Jun 95	Completed documentation

---Version 1.00:
20 Jun 95	Released to ftp.x.org

---Version 1.01:
27 Jun 95	Added user comparison functions to ordering routines
			(thanks to Kevin Carson <kcarson@direct.ca>)

---pre version 2.0
15 Aug 95	Experimental Drag & Drop using the RDD protocol
23 Aug 95	Added the double click action
25 Aug 95	Can't seem to fix the redisplay bug (Athena viewport,
			on-demand scrollbars.)  Hmmm.
		Workaround is to always show the scrollbars for Athena.
		Doesn't seem to affect Motif ScrolledWindow.
29 Aug 95	New logic for the drawing routines
 1 Sep 95	Highlight multiple entries!
 2 Sep 95	Extend action
 5 Sep 95	A few new convenience functions
12 Sep 95	Fixed the highlighting to highlight out to the widget border
15 Sep 95	Created the new callback method (ActivateCallback), but will
			keep the current method as historical.
17 Sep 95	Updating documentation
22 Sep 95	Fixed ListTreeFindChildName when item was the toplevel tree
			entry.
23 Sep 95	Added Notify procedure to call highlightCallback
27 Sep 95	More work on documentation
30 Sep 95	Final checks

---Version 2.00:
 2 Oct 95	Released to ftp.x.org