Solver test cases

[grayjay]

I cherry-picked the solver test cases from open PRs onto the solver branch (See #3357) and added issue numbers. I used tasty-expected-failure to ignore the tests that are currently failing. It doesn't seem to ignore exceptions with GHC 7.8.4, though. I can look into it later, but I didn't want to delay the PR.

/cc @edsko

[kosmikus]

@grayjay Thanks. This looks good to me, but I'll leave merging into solver to @edsko in order not to interfere with his work.

I wouldn't worry about "expected failures" too much for the time being. In fact, in the solver branch, it can even be helpful to have these as explicit failures for now, so that we can be absolutely sure we fix them all.

[edsko]

Merged, many thanks! I agree with @kosmikus , I'd say let the failing test cases just fail. After all, on this branch, if there's something failing, we should really fix it. But it's okay for now.

[grayjay]

No problem.

After all, on this branch, if there's something failing, we should really fix it. But it's okay for now.

I figured we would remove the dependency on tasty-expected-failure before merging into master, so we wouldn't miss anything.