Use the LightKit as default on the server manager.

The LightKit was already used as default in Paraview, but this default was set in the client. This created an inconsistency in lighting with pvbatch.

Change-Id: I0fab3a003b13fa39d27e012a3bf9277672b4d791
Re-enable Xdmf tests and add a new test BackgroundLights.

Xdmf test were testing a variable never set. We enable and upgrade those test to the latest controls.

Change-Id: Ib2c48f3b2ea1c92780bc46691047b617fd9a9470
Merge topic 'view-settings' into next

1b28494e Re-enable Xdmf tests and add a new test BackgroundLights.
17b7b21c Use the LightKit as default on the server manager.