TODO.txt

- Remove THREE.js from all dependencies and make it optional

- Check when cached stats should be removed; this now happens after every MCS - but this fails when stuff happens between the MCS and stat computation such that the cached stats are no longer valid (eg cell division).  

- Implement Laplacian / Gradient for 3D lattice

- Allow 3D grid to have float32 datatype just like 2D.

- Do we need to make it possible to compute stats for individual cells instead
  of for all cells at once?