librustc: Rename Owned to Send in the compiler
librustc: Change Const to Freeze in the compiler
librustc: Rename Const to Freeze
librustc: Change "Owned" to "Send" everywhere
librustc: Disallow "mut" from distributing over bindings.

This is the backwards-incompatible part of per-binding-site "mut".
libsyntax: Fix merge fallout
librustc: Add a small vector optimization for GEPi. Shaves a second off trans, I think?
auto merge of #7009 : pcwalton/rust/small-vector-gepi, r=nikomatsakis

I think this saves a second or so.

r? @nikomatsakis