Issue following #683 (closed)

Suggestions of some improvements on the legend tab:

• Under each cluster, display all the terms (not only the first 4 terms). Note: then we'll find a way to use en expand button

• Clicking on a cluster must select all its nodes on the graph view, not only the 4 first terms

• Cluster list: display all the clusters we can on the tab, so we can replace the "+" button by the rest of the clusters list

• Update the cluster list when the Louvain is launch from the toolbar : The legend should be based on the clustering that is available in SigmaJS from the font end, which means that it its update should be triggered by a click on the Louvain button.