This commits adds multiple OpenTURNS related
features, including
 * A new PARAVIEW_USE_OPENTURNS cmake option to turn on to use these features
 * A dedicated xml for some OpenTURNS filters
 * An extension to the PlotMatrixView for DensityMap capabilities
 * vtkPVHistogramView changes to support the display of OpenTurns filter output in it
 * vtkPVPlotMatrixRepresentation changes to support OpenTURNS features
 * Correction to vtkPVHistogramRepresentation to handle CenterBinAndAroundMax
 * Changes in PlotMatrixRepresentation default values to improve its look and feel
 * Modifications in Chart Management to display automatically line chart in the correct corner
 * Adding a ShowOneRepresentationAtATime xml hint
 * Adding related tests