Initial code check-in for PyQt version of Mslice

This is the initial code commit of the prototype PyQt MSlice
application. This version demonstrates conceptually how the application
would look and work, and currently is able to read-in and save Mantid
Workspaces.  However functionality to calculate projections and display
results remain to be done.
Incorporated Initial Mantid Powder Capability

* Calculate Projections for |Q|, E for Powder
* Automatically update workspace selection based upon processing to
provide workflow assistance to the user
* Application saves Matrix, IEvent, and MD workspaces
* Incorporated basic Matplotlib capability for powder slice
Incorporate Matplotlib and SliceViewer

Initial incorporation for showing slice data using both Matplotlib and
(standalone) SliceViewer.  Also included SliceViewerMainTst.py to test
sliceviewer independently.
Incorporated Workspace Algebra and updated data visualization

The ability to enter an equation using workspaces was added to the
workspace composer, and some enhancements were added for Matplotlib and
SliceViewer data visualization.
Reduced size of GUIs and refactored Workspace Composer

The MSlice GUI size was reduced by 40% and the Workspace composer was
reworked to better accommodate dataflow and workflow.
Updated Workspace Composer data load

Now data loading via the Workspace Composer operates similarly to that
in the Workspace Manager
Increasing flexibility of the Workspace Composer

Enabling users to send more than one file from the workspace manager to
the workspace composer to reduce the dependence of the workspace
composer for having to locate workspaces as files.
Corrected Sum and Eqn in Workspace Composer

Incorporated CloneWorkspace() when creating both sum and calculating an
equation so that original workspaces won't be modified.  Also updated
workspaces produced by WC to overwrite existing workspaces if they
already exist in WM.
Added Powder Cut Plot

The plot GUI is comprised of a Matplotlib figure incorporated within a
PyQt application called from the main MSlice application.