(OgreVolumeRendering): remove pepper artifacts

What does this MR do?

Cleans the black pixel artifacts that would appear at the edge of the volume. Does this by checking if ray samples are within the volume bounds.

How to test it?

• clean your build dir
• cmake . && ninja
• run OgreViewer
• load a 3D image
• this should not happen :

Associated Issues/Merge Requests

• Issues
  • Fixes #159 (closed)