Get the right-most child from node.

Property definitions

trees $ BinTreeMap :: max_from
	# Get the right-most child from `node`.
	protected fun max_from(node: N): N do
		if node.right == null then return node
		return max_from(node.right.as(not null))
	end
lib/trees/bintree.nit:138,2--142,4