NDI_STIMULUSTEMPORALFREQUENCY - given a stimulus parameter set, return the temporal frequency
[TF_VALUE, TF_NAME] = ndi.fun.stimulustemporalfrequency(STIMULUS_PARAMETERS)
Given a set of STIMULUS_PARAMETERS (a structure array), this function will
check to see if any names match those in ndi.fun.stimulustemporalfrequency.JSON.
If so, the value for this stimulus is returned in TF_VALUE and the name of
the parameter is returned in TF_NAME.
If no temporal frequency can be determined, TF_VALUE and TF_NAME are blank.