Changed: matched_intervals representation

Originally was a list of matched/mismatched intervals, the index of which would be the corresponding strong interval (column 1) index of both fingerprints 1 and 2.

Now is a list of lists, where each element is [a matched interval or nan if mismatched, index of interval in fingerprint 1, index of interval in fingerprint 2]

This should make it easier to handle comparisons of fingerprints with unequal length in the future
Added: (mismatched strong) weak comparator

Implemented using Laura's algorithm from her workflow. Needs testing when a test set is received.
Merge branch 'risk_project' of github.com:ELVIS-Project/vis into risk_project