Improve failure case for in collection

[seancorfield]

Currently, this prints an inequality failure for each non-matching element (which could be huge) and the failure message is ignored.

Also, the failed expression is not well-reported.

[seancorfield]

For reasons that I can no longer remember, (expect e (in a)) causes the underlying expect to have the arguments swapped so it essentially does (expect a' e) for each a' in a -- which means you cannot combine in with more-of (which Expectations does allow). That should probably be addressed too...