Allows the user to define a new Base Rate value, indicating the rate to which the pump under test was actually set.  The Base Rate is initially derived from the actual value of the average rate at the end of the data log file, rounded off to the nearest integer value.  The Base Rate value affects what will be reported if the graph is saved to a file or printed, and affects the Trumpet Graph calculations.  The Base Rate is equivalent to the Set Rate in the Infutest output files.