Request to add optional fail threshold to rate_of_change_test

[RobUrick]

Currently rate_of_change_test only returns Suspect flags based on a single threshold. However, for the following test in the 'Manual for Real-Time Quality Control of In-Situ Current Observations', the rate of change test requires both Fail and Suspect flags. To support this test, would it be possible to add an optional Fail threshold to 'rate_of_change_test' that would return Fail flags if it exceeds this threshold?