Simulariumio

- add conversion of MCell, MEDYAN, Smoldyn, and SpringSaLaD
- read .simularium files back in
- filters to modify the data
- filters include adding agents, getting every Nth timepoint, agent or subpoint, or transforming time or 3D space
- added support for time units, spatial units, default camera transform, and rotations data
- added benchmarks for conversion and write speed

- fix issues from user testing
- moved specific engine related files to their own modules
- fix bugs in Cytosim conversion

- conversion of Cytosim, ReaDDy, PhysiCell, and custom data
- accepts metrics data for plots
- pre user testing release