Can't use overrideParameters

[ashawley]

For a while, overrideParameters didn't work. Now that it works, it's a big benefit to users. It's also a convenience to disable shrinking.

Since it's not necessary, a lot of downstream projects don't use org.scalacheck.Properties. So I don't thinkoverrideParameters is available for people writing property tests in frameworks like Scalatest, specs2 or discipline.

So we should probably confirm this, but also document that overrideParameters is only available for direct users of ScalaCheck. I wonder if downstream maintainers should be aware of it, as well.