Eyetracker labels

These functions process the annotated labels files such that they are aligned with the eye-tracking video times. The new label files will have eyetracker sample indices instead of video frame indices.

New Files:

• eyetracker_timestamps_conversion_lib.py
• eyetracker_data_imputation.py
• eyetracker_calculate_visit_counts.py
• eyetracker_adjustment_and_visit_count_lib.py
• convert_state_frames_to_timestamps.py
• convert_annotated_label_frames_to_eyetracker_data_indices.py
• convert_annotated_label_frames_to_eyetracker_Adults_2018.py
• convert_annotated_label_frames_to_eyetracker.py
• aligndata.py

Changes:

• duplocorpus.py: Improved documentation for file I/O methods in DuploCorpus; implemented new method to read eyetracker data
• compute_stats.py, statspipeline.py, stats-setup.ini: new configuration parameter selects between video and eyetracker labels