Port `examples`, `interactions`, etc., to use the new `examples`
form of `scribble/examples`. The main intended effect is to ensure
that errors are produced by examples only as specifically
indicated.
- Coalesce repeated use of the same predicate.
- Fix scoring of Exact patterns, and scoring generally.
- Use `OrderedAnd` where needed.
- Guarantee that `and` patterns match in order.
- Thread bound variable information properly in GSeq compilation.
- Warn when variables are used non-linearly with `...`
(making this behave properly was not backwards compatible).
Closes#952, which now runs in <1ms and make it a test case.
Also add margin note about `?` patterns and multiple calls.
