Out Canv: Migration of OutputCanvasScene to OutputCanvasGfxItemMgr [1]
Bug Number: n/a
Release notes (y/n): no
For Release Nums: 7.1

Project: USACE ABQ 5.11: Output Canvas Items on Workspace views
http://cadswes2.colorado.edu/~philw/2017/CoeAbq5p11/proj.html

Architectural Preparation: Extract from OutputCanvasScene the management of 
the contained QGraphicItems into a class which can be shared with 
WorkspaceGfxScene.

New module:
  Sim/OutputCanvasGfxItemMgr.hpp
  Sim/OutputCanvasGfxItemMgr.cpp

The entire implementation of QtUtils/OutputCanvasScene (a QGraphicsScene) 
has been moved out to a new class, QtUtils/OutputCanvasGfxItemMgr (just a 
QObject -- i.e. not even a QWidget).  OutputCanvasScene now manages an 
instance of the new class.  This can also now be done from WorkspaceGfxScene.

OutputCanvasGfxItemMgr still functions for exactly one OutputCanvasConfig.

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