Rate of change option for dynamic arrays

[EdmundStephens]

[v2021.10.2] Suggestion to add a Difference Option for 'Rate of Change'. This would difference the array data from the previous restart point time step divided by the time step size. For example the rate of change of the pressure would be the depletion rate. In the Difference Options panel, what might work nicely is a drop down to control the time units: i) not divide by the time step (can be default, i.e. just display the difference), ii) delta time in seconds, iii) delta time in hours, iv) delta time in days, v) delta time in years.