Improve error message for a handwritten Typeable instance
Test Trac #9747
Add comments explaining ProbOneShot
Test Trac #9739
Fix the superclass-cycle detection code (Trac #9739)

We were falling into an infinite loop when doing the ambiguity
check on a class method, even though we had previously detected
a superclass cycle.  There was code to deal with this, but it
wasn't right.
Comments only
Testsuite error message changes
Add flattening-notes
Make this test a bit simpler

There were two unrelated functions, and the `-ddump-rule-firings` output
was coming in a non-deterministic order as a result. So now there is just
one function.
Work in progress