auto merge of #12348 : brunoabinader/rust/libcollections-list-refactory, r=alexcrichton

This PR includes:
- Create an iterator for ```List<T>``` called ```Items<T>```;
- Move all list operations inside ```List<T>``` impl;
- Removed functions that are already provided by ```Iterator``` trait;
- Refactor on ```len()``` and ```is_empty``` using ```Container``` trait;
- Bunch of minor fixes;

A replacement for using @ is intended, but still in discussion.

Closes #12344.

Author: bors

src/doc/rust.md

@@ -3256,10 +3256,10 @@ An example of a *recursive* type and its use:
 ~~~~
 enum List<T> {
   Nil,
-  Cons(T, @List<T>)
+  Cons(T, ~List<T>)
 }
 
-let a: List<int> = Cons(7, @Cons(13, @Nil));
+let a: List<int> = Cons(7, ~Cons(13, ~Nil));
 ~~~~
 
 ### Pointer types

src/libarena/lib.rs

@@ -25,7 +25,6 @@
 extern crate collections;
 
 use collections::list::{List, Cons, Nil};
-use collections::list;
 
 use std::cast::{transmute, transmute_mut, transmute_mut_region};
 use std::cast;
@@ -44,7 +43,7 @@ use std::vec;
 // The way arena uses arrays is really deeply awful. The arrays are
 // allocated, and have capacities reserved, but the fill for the array
 // will always stay at 0.
-#[deriving(Clone)]
+#[deriving(Clone, Eq)]
 struct Chunk {
     data: Rc<RefCell<~[u8]>>,
     fill: Cell<uint>,
@@ -119,13 +118,11 @@ impl Drop for Arena {
     fn drop(&mut self) {
         unsafe {
             destroy_chunk(&self.head);
-
-            list::each(self.chunks.get(), |chunk| {
+            for chunk in self.chunks.get().iter() {
                 if !chunk.is_pod.get() {
                     destroy_chunk(chunk);
                 }
-                true
-            });
+            }
         }
     }
 }