Sort an Array of related Objects so that parents always precede their children
/**
* @param {Object[]} nodes an array of objects that need to be sorted
* @returns {Object[]}
*/
return function sortLeavesLast(nodes)The nodes may have 0..n children. For my use case, nodes may also have 0..n parents. However, for all nodes, there must be no intersection between the sets of parents and children (no grand-father paradox!).
The Array of nodes may includes nodes from multiple distinct graphs.
For these purposes, a Node is an Object with the parentNodes and
childNodes properties are Arrays (empty or only containing other
Nodes). The Array of Nodes passed to sortLeavesLast must contain all
Nodes in the graph.