Starting afresh, initial skeleton of inelastic reducer.  Non-functional - just committing for safety.  refs #2849

Refs #3203: Fix occasional segfault in ConvertToMatrixWorkspaceTest due to a little error in CRITICAL block names for OpenMP thread safety. One character fix :)

Fixes #3321: deprecated DiffractionFocussing1. Fix tests in release version (refs #3203). Fix a few warnings Refs #3302.

Q vectors from the sorted list, rather than from the
original list.
refs #3205

re #3248 Bring EventNexusReader up to the same level as the RebinningCutter filter in terms of use of ThresholdRange and associated controls.

- Refs #3203: Implemented ISpectrum. It is the base class of EventList and Histogram and contains the spectrum number and list of detector IDs for a given spectrum.
- ISpectrum return X/Y/E vectors. EventList, e.g. calculates the histogram on the fly.
- Moved the EventWorkspace MRU list of histograms to be contained within the EventList; better code separation. Made a EventWorkspaceMRU class to encapsulate this more easily.
- Workspaces must implement getSpectrum (const/not const) to return a ISpectrum object. dataX(i), etc. methods on MatrixWorkspaces no longer need to be overridden since they call getSpectrum()
- Got rid of EventWorkspace::getEventListatPixelID() and doneLoadingData()
- replaceSpectraMap() methods offers backwards-compatibility with SpectraDetectorMaps by setting the specNo and detector list when called. Must be called AFTER creating all the spectra in a workspace.
- Refs #3318: maskWorkspaceIndex() implemented as part of ISpectrum.

re #3248 #3319. Reorganise controls. For rebinning cutter, wire-up selections made of different Thresholding Strategies.

Added the Save button to the mask tab for exporting masking either to a workspace or a file. re #2249

a huge list of possible orientations to find a UB that indexes 
a small subset of low magnitude Q vectors.  It then does a
least squares refinement on the UB, and gradually increases the
number of peaks to be indexed by adding Q vectors with increasing
|Q|, doing a least squares refinement at each step.  The number
of low |Q| peaks to be initially indexed and the distance between
possible orientations are controlled by parameters.
refs #3205