add naturalistic memory metrics

[andrewheusser]

We developed a few interesting memory metrics for the sherlock paper, which would be relatively easy to port into quail:

1. Precision: how precisely the recall events match the video events

• the mean correlation between each recall event and the highest matching video event (can also be computed on a per event basis)
• code: [np.max(1 - cdist(video_events, r, 'correlation'), 0).mean() for r in recall_events]

2. Distinctiveness: how distinctive the recall events are from other recall events

• the mean of the upper triangle of the recall event correlation matrix (can also be computed on a per event basis)
  -code: [1 - np.triu(np.corrcoef(r)).mean() for r in recall_events]

3. Recall autocorrelation: the rate at which the recall content changes over time

• the autocorrelation of the recall matrix (not recall event matrix)