Remove AnyRef, AnyVal, and Nothing type hints

because they don't really mean anything.
Add Vector append operation
Support structure sharing for Vector-initialized VectorBuilders
Add ArrayBuilder to facilitate Array-compatible collections
Add strict append and prepend macros

for Seq types, including length-hinted versions for arrays and indexes.
Move ArrayBuilder to the collections package to make it container
independent. Also restrict concatenation macros to like-types; you can
always concatenate arbitrary collections by ascripting the more
specific argument to the less specific type.
Disuse all Scala-2.10.1 deprecations

and remove all SI-6482 workarounds.