Choose timeout based on runtime on initial test case #23
Description
Currently shrinkray has a default timeout and complains if your initial test case takes longer than that. This mostly seems unreasonable. The main benefit of the timeout is that it stops you accidentally creating infinite loops. Shrinkray won't behave great on very slow interestingness tests, but if your interestingness test is very slow there's probably not much you can do about that and it's better for shrinkray to just let it run.
A better approach would be to run the initial test case with some very lenient timeout (say, 5 minutes), and set the timeout that shrinkray runs with to, say, 10x the time it takes for that initial test case. This means that the default behaviour is that you get the infinite loop protection but shrinkray doesn't yell at you about problems you can't do anything about.