OpenGL error hunt pv

This patch implements consistent OpenGL error checking used in VTK
in ParaView and cleans up reported errors.

Change-Id: I00a0774e89f7ad0daa8679808cb1fb141c9b794f
Merge topic 'update_vtk_master' into next

c8736fa OpenGL error hunt pv
Update VTK to bring in latest vtk-master.

Change-Id: Ib426ba7409b06c390c4a5be7f17b7f7da3c65af1
Merge topic 'update_vtk_master' into next

4bcf49d Update VTK to bring in latest vtk-master.
Add PythonQtPlugin files.

The PythonQt plugin makes the Qt API available to users from the
ParaView Python console.  The plugin uses the PythonQt library.  The
PythonQt homepage is pythonqt.sourceforge.net.

Note, PythonQt is different from PyQt4, it is a separate project and
uses a different technique to generate Qt bindings.

For more information, see the included README.

Change-Id: I05cd20422a4777866fbd1a5bc21783a6e06c2482
Merge topic '14179-add-PythonQt-plugin' into next

4ccede3 Add PythonQtPlugin files.