BioAlgorithm.score is never used (?)

Hi, I believe that following this commit, the BioAlgorithm.score might never be explicitly called (scoring is always passing through BioAlgorithm.score_multiple_biometric_references). This is unless there is some usage I am not aware of, but I think scoring in vanilla-biometrics is always done through BioAlgorithm.score_samples, which itself never calls score.

This might become confusing for users as the doc only mention the BioAlgorithm.score (which moreover is abstract), while the main thing to implement in a BioAlgorithm is actually the BioAlgorithm.score_multiple_biometric_references (which moreover is not abstract).

ping @amohammadi , this is related to the first question in issue #153 (closed). But I think it's better that I open a separate issue for clarity. ping @hotroshi