[Feature Request] processProperties for edges when clustering

[nitzanbueno]

When clustering nodes, using processProperties, I can give the new cluster dynamic properties based on its child nodes.

The same can't be done with edges, however. I want to be able to change the cluster edge properties individually, based on their base edges. Currently I can only update the dataset after the clustering is done.

Next to the processProperties parameter in cluster, I'd like a processEdgeProperties(edgeProperties, childEdges) parameter that will return the new cluster edge properties.