Simple Abelian sandpile model
Algorithm implemented from Wikipedia's sandpile article as seen on The Coding Challenge #107: Sandpiles.
This implementation utilizes the DirectBitmap class, which I introduced a while back and although it is extremely fast when you want to manipulate individual pixels and it’s 100% thread safe, it also lacks any type of aliasing support, so don't expect the results to look as nice as they do on the aforementioned articles/videos.