Merge topic 'fix-mpi-finalize'

3a80e90b Prevent vtkProcessModule from calling MPI_Finalize() twice
Merge topic 'pvw-fix-webgl-vgl-issues'

76d5c64d Fix WebGL rendering issue
Merge topic 'vtkweb-catalyst-delayed-exit-and-alternate-launch'

56052c08 Move VTK forward to improve catalyst browser web widget and wamp.py
Merge master into next

* commit 'aa525d5d662ea6c7036e47a07e4c8a146a773e5f':

Change-Id: I6ae73d81f8645d04210dd1c9dbb2dc9f4ef65ed9
Add exporter mechanism for catalyst

This allow users to register arbitrary data exporter
which will then be called after each timestep to
export or process the data the way they want.

They just need to implement the 2 following methods:

   UpdatePipeline(time)
   Finalize()

Change-Id: Iabad816c3fac4a3ff60fffccf6fd59051fff8d27
Merge topic 'add-flexibility-to-catalyst-exporter' into next

4fc7d363 Add exporter mechanism for catalyst
Calling finalize on existing Catalyst pipelines.

Change-Id: Ib06c8c52f8e3f79690b697ec4e805b494d3801c1
Merge topic '14990_finalize_catalyst_pipelines' into next

5599635d Calling finalize on existing Catalyst pipelines.
Fix 14931: The Histogram filter does not Calculate Averages by default.

Change-Id: I941adcf213d1d983bd608fa93184b9c0ee915eae
Merge topic '14931-cluttered-histogram' into next

05ce7d45 Fix 14931: The Histogram filter does not Calculate Averages by default.
Add an 'CalculateAverages' to XYHistogram test.

This property is not set by default now.

Change-Id: Ie5d7589b9b9b46e9e81b7c3327c4d971392a111f
Merge topic '14931-cluttered-histogram' into next

65ac40d4 Add an 'CalculateAverages' to XYHistogram test.