GRMERGENODESMEDIAN Replace several nodes by their median coordinate.

   [NODES2, EDGES2] = grMergeNodesMedian(NODES, EDGES, NODES2MERGE)
   NODES ans EDGES are the graph structure, and NODES2MERGE is the list of
   indices of nodes to be merged.
   The median coordinate of merged nodes is computed, and all nodes are
   merged to this new node.

Package: matgeom