introduced sparseClustering3 algo
sparseClustering3 does now the same (stupid) cuts as sparseClustering(2)
Fixed bug reported by @mkofarag in sparseClustering
Renamed _sparse3MinDistance to sparseMinDistanceSquared
Renamed _sparse3MinDistance to sparseMinDistanceSquared
Merge pull request #59 from tbisanz/sparseClustering3

Introduced sparseClustering3 algorithm