Modifies "maybeRewrap" to focus more on the maybe.

Existential types are rewrapped under a bunch of conditions
unless the operation performed on the underlying type returns
the same type by reference equality. That depends on a
foundation of predictability which doesn't exist. The upshot is
that existential types were rewrapped with abandon, even when
the type were identical.

This had both performance and correctness implications.
Note where the test case output changes like so:

  -scala.collection.immutable.List[Any]
  +scala.collection.immutable.List[<?>]

That's correctness.
SI-6979 Small optimization in lub

If a member of `lubBase` is final, it cannot be
refined in the types we're lubbing.
align partest script with ant

don't silently pass -deprecation to scalac by default
SI-6811 Remove scala.annotation.serializable

Every usage of it has been eliminated in earlier commits,
so the source file can finally be removed, too.
SI-6811 Remove usages of scala.annotation.cloneable

The source file itself will be removed later,
because the compiler seems to need it for boot-strapping.
SI-6811 Remove deprecated constructors
SI-6811 Remove primitive widenings and /:\
SI-6811 Remove scala.collection.mutable.ConcurrentMap
SI-6811 Remove the scala.util.grammar package
SI-6811 Remove parts of scala.concurrent not needed by scala.actors
SI-6811 Remove deprecated elements in scala.collection
SI-6811 Misc. removals in util, testing, io, ...
SI-6811 Remove the scala.annotation.target package
SI-6811 Remove scala.ScalaObject
Disable MIMA in master.

Binary compatibility checks do not make sense in master because
there's no base point against which we should check.
Remove the term "pimp" from the repository

Small terminology change aimed at improving inclusion.
Grammatical fix
Merge pull request #1926 from gkossakowski/disable-mima-in-master

Disable MIMA in master.
Merge pull request #1908 from retronym/ticket/6979

SI-6979 Small optimization in lub
SI-6811 Remove scala.xml.include.sax.Main