Rework the track and improve data selection

See merge request !301

1) Command line arguments simplified.
2) Indexing to allow tracing back to original data points.
3) We now drop rows with nan in them.
4) Enabling the vtkCameraOrientationWidget.

1) Adding "Track" for Track Name.
2) Adding "nan" for missing numeric data.

Updating the file handling and instructions

See merge request !300

Updating the csv readers

See merge request !299

Initial commit of the python files

See merge request !298

Add find_package() to the documentation in the Developers section

See merge request !297

Adding ContourTriangulator.py

See merge request !296

Cxx: Add OpenVR volume rendering example

See merge request !295

Fix OpenVR cone example (initialize got lost in merge)

See merge request !294

OpenVR: Add note about how to enable interactions

See merge request !293

Use vtkNew in OpenVRCone

See merge request !292

# Conflicts:
#   src/Cxx/GeometricObjects/OpenVRCone.cxx

Fix OpenVR sphere example

See merge request !291

# Conflicts:
#   src/Cxx/GeometricObjects/OpenVRSphere.cxx

Fix OpenVR initialization (fixes crash on VTK >= 9.1)

Closes vtk#18433

See merge request !290

For the interaction to work in the OpenVR examples,
it is required to copy the action/manifest .json files
to the working directory. This adds an according note
to the description of these examples