Render only valid data in charts

This fixes a bug in which the charts would render invalid
points/data. This updates the charting/ploting classes to make
use of the vtkValidPointMask array and only render valid data.

Change-Id: Ic0ab56dc5422b73253a6ef56d1f32e122a002335
Merge topic '14098-skip-invalid-points' into next

988412c Render only valid data in charts
Add range slider widgets from ctk

This adds both double and integer double-ended range slider from the
common toolkit CTK (https://github.com/commontk/CTK).

The versions of files imported from CTK come from CTK
revision. 71c756a32052f1f04cf10b111a18826e95347d34

The changes made to the headers include removing CTK headers that were
unused and updating the export macro for the appropriate paraview
library.  Additionally the paraview license was prepended.

Change-Id: I53fe3c13c8bddeb1551423d4eda422a3bea5072f
Basic test for CTK range sliders

This test does not verification of the code as that is assumed to be
tested in CTK.  Instead this provides a simple example that can be run
to illustrate the use of the two widgets.

Change-Id: I96d934429331e3328d728cdb793ccc48441d601e
Merge topic 'double_slider' into next

199bca5 Basic test for CTK range sliders
4d8bb08 Add range slider widgets from ctk
Fix shadow and default assignment warnings

Change-Id: Ibafb4c1b3b915d69713aa8ec7a97cc70ba7b9c2e
Merge topic 'double_slider' into next

9b8f323 Fix shadow and default assignment warnings
Warning fixes for shadowing

Change-Id: I73740896ddd6f19206d4559fa6d589f24dd6c451
Merge topic 'double_slider' into next

fece498 Warning fixes for shadowing
Shadow warning fixes

Change-Id: I0ba3b9dd68ab296b178764259aec975f248675da
Merge topic 'double_slider' into next

7b4c04b Shadow warning fixes