collections: Move push/pop to MutableSeq

Implement for Vec, DList, RingBuf. Add MutableSeq to the prelude.

Since the collections traits are in the prelude most consumers of
these methods will continue to work without change.

[breaking-change]
collections: Deprecate push_back/pop_back
Convert some push_back users to push
collections: Move push/pop docs to MutableSeq
vim: Add MutableSeq
collections: Make push_back/pop_back default methods
collections: Deprecate shift/unshift

Use insert/remove instead.
Remove kludgy imports from vec! macro
collections: Tweak docs for push
Remove stray llvmdeps.rs
Just land already
auto merge of #15611 : brson/rust/pushpop, r=alexcrichton

This fixes naming conventions for `push`/`pop` from either end of a structure by partially implementing @erickt's suggestion from https://github.com/rust-lang/rust/issues/10852#issuecomment-30823343, namely:

* push/pop from the 'back' are called `push` and `pop`.
* push/pop from the 'front' are called `push_front` and `pop_front`.
* `push`/`pop` are declared on the `MutableSeq` trait.
* Implement `MutableSeq` for `Vec`, `DList`, and `RingBuf`.
* Add `MutableSeq` to the prelude.

I did not make any further refactorings because there is some more extensive thought that needs to be put into the collections traits. This is an easy first step that should close https://github.com/rust-lang/rust/issues/10852.

I left the `push_back` and `pop_back` methods on `DList` and `RingBuf` deprecated. Because `MutableSeq` is in the prelude it shouldn't break many, but it is a breaking change.
auto merge of #15407 : sneves/rust/master, r=aturon

At the moment, writing generic functions for integer types that involve shifting is rather verbose. For example, a function at shifts an integer left by 1 currently requires 

    use std::num::One;
    fn f<T: Int>(x : T) -> T {
        x << One::one()
    }

If the shift amount is not 1, it's even worse:

    use std::num::FromPrimitive;
    fn f<T: Int + FromPrimitive>(x: T) -> T {
        x << FromPrimitive::from_int(2).unwrap()
    }

This patch allows the much simpler implementation

    fn f<T: Int>(x: T) -> T { 
        x << 2
    }

It accomplishes this by changing the built-in integer types (and the `Int` trait) to implement `Shl<uint, T>` instead of `Shl<T, T>` as it currently is defined. Note that the internal implementations of `shl` already cast the right-hand side to `uint`. `BigInt` also implements `Shl<uint, BigInt>`, so this increases consistency.

All of the above applies similarly to right shifts, i.e., `Shr<uint, T>`.
auto merge of #15781 : alexcrichton/rust/issue-15758, r=bblum

Semaphores are not currently designed to handle this case correctly, leading to
very strange behavior. Semaphores as written are intended to count *resources*
and it's not possible to have a negative number of resources.

This alters the behavior and documentation to note that the task will be failed
if the initial count is 0.

Closes #15758
auto merge of #15862 : jakub-/rust/issue-15774, r=alexcrichton

Fixed #15774.
auto merge of #15909 : colemickens/rust/patch-3, r=alexcrichton

Tested this on the playground, the range specifies range(0u, 3), so it should be okay to remove this cast.
Fill in example code for HashMap.

Add an example showing how to use the map with a custom type. Fill in
examples for methods in the hashmap file without ones.

Also move pop_equiv next to related public methods, to not create a
duplicate trait implementation in the docs.
Remove explicit rust code specifier. Unhide use HashMap.
Move contructors to the top of PriorityQueue.
Document PriorityQueue.