Added proxy weighting #2012

Proposing adding proxy weighting to the current release branch, although I could be convinced otherwise.
This nondeterminism violates the `Comparator` contract by making the "ordering" not a total order.

https://docs.oracle.com/javase/7/docs/api/java/util/Comparator.html

Strictly speaking, the result of using this with `sort` is undefined.  Intuitively I think it should work well enough.  But I think a warning comment is warranted at least.