add naturalistic memory metrics

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)