Figure out the definition ord Ord/Eq, TotalOrd/TotalEq

[brson]

I see all kinds of issues that propose specific solutions, but none that are still opened. We need to be happy with these traits for 1.0.

Dropping this etherpad here for lack of another place to put it: https://etherpad.mozilla.org/uaxtsKwv8w. It contains an audit of which code is using which traits, and some notes on use cases.

Nominating.

[brson]

We need somebody to lay out the design of the 2 or 3 good options.

[pnkfelix]

Closing as dupe of #12517.