rustc: Remove CrateId and all related support

This commit removes all support in the compiler for the #[crate_id] attribute
and all of its derivative infrastructure. A list of the functionality removed is:

* The #[crate_id] attribute no longer exists
* There is no longer the concept of a version of a crate
* Version numbers are no longer appended to symbol names
* The --crate-id command line option has been removed

To migrate forward, rename #[crate_id] to #[crate_name] and only the name of the
crate itself should be mentioned. The version/path of the old crate id should be
removed.

For a transitionary state, the #[crate_id] attribute is still accepted if
the #[crate_name] is not present, but it is warned about if it is the only
identifier present.

RFC: 0035-remove-crate-id
[breaking-change]

src/libsyntax/ext/base.rs

@@ -452,7 +452,7 @@ impl<'a> ExtCtxt<'a> {
     pub fn mod_pop(&mut self) { self.mod_path.pop().unwrap(); }
     pub fn mod_path(&self) -> Vec<ast::Ident> {
         let mut v = Vec::new();
-        v.push(token::str_to_ident(self.ecfg.crate_id.name.as_slice()));
+        v.push(token::str_to_ident(self.ecfg.crate_name.as_slice()));
         v.extend(self.mod_path.iter().map(|a| *a));
         return v;
     }