Remove a no longer necessary `impossible`
Make tests work with sandboxes
Fix GC statistics overflow
Reduce redundant 'specifically' clauses in errors
Update expected error messages for tests
Need to resolve autos in each 'try' branch

If the branch solves an implicit which makes the auto solvable, we need
to try to resolve it straight away so we know whether the branch is
valid or not. We need this especially when using 'try' to implement
implicit coercions.
Define Show instance for Vect via toList.
Merge pull request #1712 from Melvar/remove-impossible

Remove a no longer necessary `impossible`
Merge pull request #1755 from mattias-lundell/master

Make tests work with sandboxes and fix GC statistics overflow
Merge pull request #1761 from bmsherman/dontDupErrors

Reduce redundant 'specifically' clauses in errors
Merge pull request #1763 from ziman/show-vect

Define `Show` instance for `Vect` via `toList`
Check target of 'with' is a value (not a function)