Implementation for "Copy Qualified Name" (#1001257)

This is a first implementation for "Copy Qualified Name". The GUI interacts with ScalaCopyQualifiedNameAction, with extends and eventually delegates to the corresponding Java class. The actual works happens in NamePrinter.

I'm still planning to do some tweaks/changes/feature additions, but I wanted to share this with you early.
I might need some help to get this test working (the desired behavior is modeled after what Eclipse does for Java): How can I obtain the enclosing DefDef (if any) of a given Tree?