Fix missing word.
Rename an include file.
Calculate some sort of exposure to the film.
Removed the beam type and use the ray type from the geometry.
Rename the guards.
Shader skeleton.
Add background colour to the scene.
Remove the moveable abstract base class as it's not needed.
Remove pointer indirection and memory allocations.
Refactor the sphere type.
Small change to the background colour.
Include details of some Ubuntu packages that are needed.
Start to put in a more sophisticated surface physics layer.