Build a 3D LocalParticle.

[jdaymude]

Now that the 3D simulator has many of the important pieces of the base Particle class, we need to step one level up to LocalParticle, the class responsible for obfuscating global information from the particles in an effort to keep all directional information local. The necessary functions can all be taken from the 2D simulator's LocalParticle class, but the implementations will need to change to address the immensely more complex 3D space.