Simulation updates were one step of calculation and merging the calculations into the map in one function.
Separating the two allows checking for a new update without affecting the grid, allows passing the last Update around and allows custom changes to the grid by passing changes to the merge function that were not derived from the update function.
Cells are now only an empty struct, they carry no information beyond needing to be re-rendered. All Simulation logic is handled in the Simulation Class.
