SI-6896, spurious warning with overloaded main.

Make sure there's no legit main signature before issuing
any warnings about missing main methods.
SI-6897, lubs and varargs star.

Don't allow lubs to calculate refinement types which contain
a varargs star outside of legal varargs star position.
SI-6911, regression in generated case class equality.

Caught out by the different semantics of isInstanceOf and
pattern matching.

  trait K { case class CC(name: String) }
  object Foo extends K
  object Bar extends K
  Foo.CC("a") == Bar.CC("a")

That expression is supposed to be false, and with this
commit it is once again.
proper elementClass for WrappedArray

(backport of 45ef0514e, part 1)
avoid reflect overhead of certain array instantiations

the manifests for Any, Object/AnyRef, AnyVal, Null and Nothing
now have their `newArray` methods overridden to avoid reflective overhead
of array instantiation.

(backport of 45ef0514e, part 2)
Merge pull request #1840 from paulp/issue/6911

SI-6911, regression in generated case class equality.
Merge pull request #1835 from paulp/issue/6896

SI-6896, spurious warning with overloaded main.
Merge pull request #1834 from paulp/issue/6897

SI-6897, lubs and varargs star.
Merge pull request #1842 from adriaanm/backport-1821

Backport 1821
SI-6928, VerifyError with self reference to super.

A bug in typers mishandled varargs. We should get more
aggressive about eliminating all the ad hoc parameter/argument
handling code spread everywhere. For varargs especially:
any code which tries to make an adjustment based on a
repeated parameter is more likely to be wrong than right.
In aggregate these reinventions are a huge source of bugs.