Minor bugfixes for CLI level use
v0.13-release
Since the core dependency of fipy is now usable directly in python3, microbenthos is now considered python3-only software (> python 3.6)
Time-stepping heuristics were improved to deal with numerical instabilities for stiff differential equations. API remains unchanged, though there are behavioral changes in running Simulation.run_timestep and Simulation.evolution.
Other small improvements in the submodules.