Enhancement of the web chart vizualization

Currently, vizualization of the results of a specific annotator in the circle chart (http://gerbil.aksw.org/gerbil/overview) is not very user friendly, especially because similar colors are used for similar annotators. It would be nice if one could click on one specific annotator (or a sub-list of annotators) in the right list (showing associated colors) and only its (their) results will be shown in the circle chart diagram.

Start at the overview page and locate the circle-chart implementation and the right-hand annotator list; the issue does not name specific files or tests. Trace how annotator colors and results are assembled, then verify that selecting one or more annotators filters the chart while preserving the existing overview behavior.

Written by the indexing model from the issue text.