This PR refactors `Lean.Grind.NatModule/IntModule/Ring.IsOrdered`.
We ensure the the diamond from `Ring` to `NatModule` via either
`Semiring` or `IntModule` is defeq, which was not previously the case.
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Co-authored-by: Leonardo de Moura <leomoura@amazon.com>
This PR adds doc-strings to the `Lean.Grind` algebra typeclasses, as
these will appear in the reference manual explaining how to extend
`grind` algebra solvers to new types. Also removes some redundant
fields.
This PR introduces the basic theory of ordered modules over Nat (i.e.
without subtraction), for `grind`. We'll solve problems here by
embedding them in the `IntModule` envelope.
This PR adds `Lean.Grind.Ring.IsOrdered`, and cleans up the ring/module
grind API. These typeclasses are at present unused, but will support
future algorithmic improvements in `grind`.
