Simpler IgnoringDifferenceListener.
A BronKerboschMergeJob with fewer edge cases needing arbitrary
decisions. This makes the description simpler, the implementation easier
to follow, and testing WAY easier. More importantly, it more closely
follows the underlying implications of homology.
Gave DistanceClusterer a more reasonable interface
Removed delta, which we're no longer using.
Merge branch 'master' of https://github.com/dmyersturnbull/network_merge.git