Adapt Cylinder source lookup method to FiberCone source to speed-up simulation time
The cylinder source uses an RTree to look for the tetrahderons that it emits its photons from. By doing it naively, you can get long runtimes because the lookup time in themesh dominates everything else.
The FiberCone source has a similar problem to the naive implementation. We could adapt the RtRee lookup to the FiberCone and would be able to speedup large FiberCone sources quite a bit.
The other option, would be to try to do pre-processing and essentially create a composite source of all tetrahedrons inside the Fibercone definition.