Cell and intracellular events that can occur within a simulation cycle.

*This event exists only within the ISMA system and has no
specific cystogenesis counterpart.
All cell events produce a visible change within the ISMA
visualization. Events that map to intracellular events result in a
change within a cell, but do not produce a visible change
within the ISMA. Cell-level events map to equivalent events
between in vitro MDCK cells, lumen, and matrix, while
intracellular events map to events (less well
understood) within in vitro MDCK cells.