Fixed examples

The examples were still using `core::` instead of `std::`
All of the examples needed a `use std::rand;` at the top to compile
Most of the examples had
    `rng = rand::rng();`
instead of
    `let mut rng = rand::rng();`
Add a `mut_split()` method for dividing one `&mut [T]` into two
Implement SIMD arithmetics
Change the assert_eq message to be more verbose.

Closes #6221
fix test
Add an identifier to TypeParameterDefs and use it to pretty print type parameters
auto merge of #7631 : MarkJr94/rust/ptr_arithmetic, r=thestinger

Added Add and Sub traits for pointer arithmetic. Any type that is a ```std::num::Int``` can be added to or subtracted from a pointer. Also my additions did not require any unsafe code, and the operators themselves are safe. Fixes #2122.
auto merge of #7698 : nikomatsakis/rust/issue-2951-type-parameter-names, r=cmr

Fixes #2951
auto merge of #7683 : alexcrichton/rust/issue-7625, r=thestinger

Closes #7625
Convert json Reader to iterators

This is much faster for strings, and eventually when there is a
buffered reader of some sort.

Reading example.json 100 times before was around 1.18s.
After:
- reading from string 0.68s
- reading from file 1.08s (extra time is all in io::Reader)
Add a compile-fail test for qualification lint
auto merge of #7690 : kevinmehall/rust/document-c_void, r=huonw

I added documentation for when to use and not to use `c_void`, since it tripped me up when I started. (See issue #7627)
remove unused imports
unnecessarily mutable variables
unused variable
iterator: add DoubleEndedIterator concept

This implements the trait for vector iterators, replacing the reverse
iterator types. The methods will stay, for implementing the future
reverse Iterable traits and convenience.

This can also be trivially implemented for circular buffers and other
variants of arrays like strings and `SmallIntMap`/`SmallIntSet`.

The `DoubleEndedIterator` trait will allow for implementing algorithms
like in-place reverse on generic mutable iterators.

The naming (`Range` vs. `Iterator`, `Bidirectional` vs. `DoubleEnded`)
can be bikeshedded in the future.
vec: rm inline(never) hack

just avoid giving an inline hint in the first place
auto merge of #7691 : nikomatsakis/rust/vec-split-method, r=thestinger

I don't think we have this yet. This makes `&mut [T]` much more flexible.

r? @strcat (or whomever)
Work around stage0 to remove '@' requirements from TLS
Fix a soundness problem with `get`