Fixed filter showResults+ selection.

Now filtered clusters also selects the longest one for overlapping clusters (in addition to best pscore and best dcj similarity).

GUI fix that prevented dcj computation for all clusters being canceled when each individual computation task finished too quick.

Heuristics for DCJ similarity calculation

See merge request !1

Now showFiltered shows not only the cluster with best pscore for overlapping clusters, but also the cluster with the best average DCJ similarity.

orientation).