Improvements in Find References

This is a bunch of commits that need more work, but I think they're important and improve at least some cases.

* `ScalaMatchLocator` should recurse into trees with transparent positions. 
* better matching of parameter names in `ScalaJavaMapper`. This one I am not sure is correct, it would be good to get a second opinion. My fix allows finding methods that take parameters with an `Array` type (that were not found before).
* a few test cases would help.

It would be cool if someone took this over. Help? :)