extirpate all references the "queen" and "metatracker"

extirpate all references the "queen" and "metatracker"
This is a potentially disruptive and potentially ugly change to the code base,
because I renamed the object that serves in both roles from "Queen" to
"IntroducerAndVdrive", which is a bit of an ugly name.

However, I think that clarity is important enough in this release to make this
change.  All unit tests pass.  I'm now darcs recording this patch in order to
pull it to other machines for more testing.