auto merge of #13958 : pcwalton/rust/detilde, r=pcwalton
auto merge of #13958 : pcwalton/rust/detilde, r=pcwalton

for `~str`/`~[]`.

Note that `~self` still remains, since I forgot to add support for
`Box<self>` before the snapshot.

r? @brson or @alexcrichton or whoever

rust-lang-nursery/uuid,rust-lang/uuid,nixpulvis/uuid,mathstuf/rust-uuid,tomprogrammer/uuid