Move clustering_report to omnibenchmark

[DanInci]

We might want to move https://github.com/imallona/clustering_report to omnibenchmark such that is part of the example clustbench.

[imallona]

Not until Mark / someone does proper plots, mine are really preliminary / not for production. I plan another clustbench work week in May/June, but not yet.