New Body Plan: Clean up
Refactor
Add performance test

Currently scoring 1000 cycles in a little more than 18 seconds.
Cache Vector methods for performance

Performance test is down to around 16 seconds from 18 seconds.
Parallelize ticking of narjillos

First stab at parallelizing Narjillo ticking. I still need to check the
code, clean it up, and syncrhonize relevant Narjillo methods.
Fix bug with body plan tree structure

The body tree contained the wrong relationships between parents and
children. As a result, the same body segment was being added multiple
times. This explained both the sudden drop in performance (I had
thousands of unnecessary body part physics calculations) and the failure
of the "non-deterministic experiment" test (which had to do with the
fact that the same object was being serialized multiple times, and
was then deserialized as multiple equal but not identical objects).