Skip rendering of invalid points in PlotLine/PlotPoints

This adds code to skip the rendering of bad points in vtkPlotLine
and vtkPlotPoints. Also allows adding additional bad points with
a mask array.

This is used by the plot-over-line filter in ParaView to skip
rendering of points which are not a part of the data set.

Change-Id: Iba014e7299e9dd47caec2582ca40d04d21937944
Merge topic 'skip-invalid-points' into master

f562dfe4 Skip rendering of invalid points in PlotLine/PlotPoints