Montelight now does global illumination

Added:
+ Image can handle uneven number of samples
+ OpenMP for speeding up of the rendering process
+ Fixed a small bug in writing PPM files (pixel values over max allowed)

We don't yet have:
+ Russian roulette (currently it always does 4 bounces)
+ Direct emitter sampling
+ Jittered rays at the camera (hence why the light is so blocky)
+ Adaptive sampling
+ Materials other than diffuse
+ Numerous small optimizations (i.e. creating rays instead of modifying)
Instructions on compiling Montelight for *speed*!