librustc: Remove ~EXPR, ~TYPE, and ~PAT from the language, except

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

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

How to update your code:

* Instead of `~EXPR`, you should write `box EXPR`.

* Instead of `~TYPE`, you should write `Box<Type>`.

* Instead of `~PATTERN`, you should write `box PATTERN`.

[breaking-change]

src/test/compile-fail/object-does-not-impl-trait.rs

@@ -8,10 +8,11 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// Test that an object type `~Foo` is not considered to implement the
+// Test that an object type `Box<Foo>` is not considered to implement the
 // trait `Foo`. Issue #5087.
 
+
 trait Foo {}
 fn take_foo<F:Foo>(f: F) {}
-fn take_object(f: ~Foo) { take_foo(f); } //~ ERROR failed to find an implementation of trait
+fn take_object(f: Box<Foo>) { take_foo(f); } //~ ERROR failed to find an implementation of trait
 fn main() {}