Remove spurious +x on tracer.c
Split sphere scene generator from the rest of the tracer
Removed globals for list of spheres (although might not be strict ANSI C now?)
Make the lights part of the scene structure
Pulled png generation out into a separate file
Tidy up the tracing handling
Moved intersection point finding out of texturer
Pulled out sphere normal calculation from texturer
Pulled out surface lighting stuff to make implementing other surface types easier
Fix tabs and trailing spaces. Need to get emacs configured properly on this machine
Switch from 'ignore this prim' to 'ray must travel epsilon' to find next intersection
Move the normal-finding into the intersection stage
Ooops. Fix Y axis!
Check light visibility by distance, rather than surface
Added a checkerboard!
Fix the distance-based lighting visibility test
Added new executable for testing depth of field stuff
Extend the depth-of-field scene to multiple coloured balls
Implement depth of field!
Finalised image parameters for depth-of-field image