Retrieve the cluster labels from the cluster nodes

Clustering results are stored as individual gated nodes. This helper function collect all the gating indices from the same clustering run (identified by 'parent' node and 'cluster_method_name" and merge them as a single factor.

gh_get_cluster_labels(gh, parent, cluster_method_name)

Arguments

gh	GatingHierarchy
parent	the parent population/node name or path
cluster_method_name	the name of the clustering method