added tests for event_duration and event_depth in randomly generated sample data
set the event finding save_file_names
data length is seconds*sample_rate
require more events in test_number_of_events
add 1 to rate calculation so we don't get 0 rate
changed event_depth to event_depths, event_duration to event_durations
allow slightly different event counts, actual compared to found
implemented create_random_data