node.depth(phy)
node.depth.edgelength(phy)
node.height(phy)
node.height.clado(phy)phy.node.depth computes the depth of a node as the number of tips
which are its descendants. The value of 1 is given to the tips. node.depth.edgelength does the same but using branch lengths.
node.height computes the heights of nodes and tips as plotted
by a phylogram.
node.height.clado does the same but for a cladogram.
plot.phylo