MonteCarloProfileRenderer stub, templatize Vector arithmetic.
Caching matrices & fft for better CPU utilization.

At the cost of (constant) high RAM usage during profile calculation :)
Fix crash upon exit.

Potential concurrency library bug in VS2012? Anyway the code is only
called in single-threaded context, so there's no need to lock there.
Implement MCProfileRenderer.
Address numerical stability problem during RandomWalk.
Add LayeredIntegrator test scene.
Add code to generate comparison profiles using multipole.
Modify lerpOnThinSlab logic.

More accurate overall transmittance estimation using direct summation of
the kernel (possibly containing delta distribution).