Resolve "Fix OgreViewer"

What does this MR do?

This MR fixes :

• The compositor parameter channel in OgreViewer.
• SLightSelector.

How to test it?

Launch OgreViewer and check:

• Try to add a new light (without this MR it must not work).
• Check that compositor parameter are updated when you enable a compositor.
• Check that there is no crash when the application is closed and that lights have been removed.

Data

Use any VTK file.

Associated Issues/Merge Requests

• Issues

  • Closes #220 (closed)

• Merge requests

  • need : https://git.ircad.fr/Sight/sight/merge_requests/104