BF: Eyetracker missing data handled uniformly

SMI, EyeLink, Tobii and LC Tech all now use the same values in the cause
of missing sample data for gaze position fields, pupil size, and status
field:

If sample IS fine, status is == 0 now for all eye trackers.

If sample is missing data:

For monocular:

gaze_x = EyeTrackerConstants.UNDEFINED
gaze_y = EyeTrackerConstants.UNDEFINED
pupil size = 0
status = 2

For binocular:

for left:
left_gaze_x = EyeTrackerConstants.UNDEFINED
left_gaze_y = EyeTrackerConstants.UNDEFINED
left_pupil size = 0
status = 20

for right:
right_gaze_x = EyeTrackerConstants.UNDEFINED
right_gaze_y = EyeTrackerConstants.UNDEFINED
right_pupil size = 0
status += 2