Additonal changes for Help Dialog: Add help for each 'wb_command' operation.  Use a Tree Widget (hierarchy) for the help topics.  Added deletion of CommandOperationManager to wb_view.  Had to create some 'dummy OSMesa' functions for linking to the GUI.  If the real OSMesa library was linked by the GUI, it totally screwed up the GUIs OpenGL.
Fix compilation with ZLIB on John's Mac.