Changes to make the code compatible with fMRI data

The latest prior changes caused the code to handle the speech data from
fMRI sessions incorrectly, due to the existence of resting (no-speech)
trials in fMRI sessions. These changes hopefully have fixed this issue.

	modified:   cbkProcSingleTrial.m
	modified:   formantCbk.m
	new file:   get_curr_trial_index.m
	modified:   updateTrialList.m