Scala 2.11 supports

-Ywarn-dead-code -Ywarn-inaccessible -Ywarn-unused-import -Ywarn-unused -Ywarn-infer-any -Ywarn-nullary-override

These will generate warnings that allow us to clean up the code base substantially, and may catch bugs - where we have unused local values for example, but thought we were using them but aren't.