consider using `%*`, `%/`, `%^` for both types and run-time ops about coulomb HOT 2 CLOSED

Currently starting to prefer a policy where the "native" operators are all of the %* style, but define some alternative syntax aliases that people can import, if they would prefer to use more traditional *, /, etc

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value classes can't accept other value classes, so making standard numeric operators as extention would hit efficiency. Instead I'm leaving those as-is. If people want consistency of operators they can import type aliases of *, / and ^, for UnitExpr

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