Algorithm similarity eval - general implementation

[sumedhars]

As discussed - this is the general implementation only, and once this is approved - will work on the per_algo implementation

[agitter]

In addition to some minor suggestions, the one major comment is that if we have 4 algorithms with 2 parameter combinations each, we want a 8 x 8 output instead of a 4 x 4 output.

[tristan-f-r]

Superseded by #248.