Enabled progress bar during fMRI experiment (TRIGGER_BY_MRI_SCANNER == 1)

Added some comments to the two example expt_config files.

Modified the STEREO_MODE setting for the NWU-style pitch behavioral
experiments.

	modified:   mcode/expt_config.example_fmri.txt
	modified:   mcode/expt_config.example_pitch.txt
	modified:   mcode/runExperiment.m