usv-playpen v0.7.0

v0.7.0 (1) removed sync_regression and replaced it with a direct comparison of A/V IPI start times (this is also reflected in the preprocessing_plot output), (2) audio processing now saves a JSON file containing information about triggerbox input, (3) "original" audio directory is not deleted until the SYNC test reveals <18 ms (3 video frames) maximum discrepancy between A/V IPI start pulses, (4) decreased the y-dimension of the processing window, () tidied up functions throughout by adding argument names