Update comments in the prelude

The comments say that the prelude imports std::io::println since it would
be annoying to have to import it in every program that uses it. However,
the prelude doesn't actually import that function anymore. So, update the
comments to better match reality.
move enum_set to libcollections. #8784
ptr::RawPtr, spell out units used for the `offset` argument.

spell out units used for the `offset` argument, so that callers do not
try to scale to byte units themselves.
insignificant fix to rust manual and tutorial
auto merge of #12410 : DaGenix/rust/fix-incorrect-comment, r=alexcrichton

The comments say that the prelude imports std::io::println since it would
be annoying to have to import it in every program that uses it. However,
the prelude doesn't actually import that function anymore. So, update the
comments to better match reality.
auto merge of #12415 : HeroesGrave/rust/move-enum-set, r=alexcrichton

Part of #8784

Also removed the one glob import.
Move std::num::Integer to libnum
auto merge of #12419 : huonw/rust/compiler-unsafe, r=alexcrichton

Previously an `unsafe` block created by the compiler (like those in the
formatting macros) would be "ignored" if surrounded by `unsafe`, that
is, the internal unsafety would be being legitimised by the external
block:

    unsafe { println!("...") } =(expansion)=> unsafe { ... unsafe { ... } }

And the code in the inner block would be using the outer block, making
it considered used (and the inner one considered unused).

This patch forces the compiler to create a new unsafe context for
compiler generated blocks, so that their internal unsafety doesn't
escape to external blocks.

Fixes #12418.
Move time out of extra (cc #8784)
auto merge of #12420 : pnkfelix/rust/fsk-improve-doc-for-ptr-offset, r=alexcrichton

ptr::RawPtr, spell out units used for the `offset` argument.

spell out units used for the `offset` argument, so that callers do not
try to scale to byte units themselves.

(this was originally landed in PR #11002 for the stand-alone functions, but that PR did not modify the `RawPtr` methods, since that had no doc at all at the time.  Now `RawPtr` has the *only* documentation for `offset`, since the stand-alone functions went away in PR #12167 / PR #12248.)
Add Pod trait bound to std::num::Primitive
Decouple integer formatting from std::num::strconv

This works towards a complete rewrite and ultimate removal of the `std::num::strconv` module (see #6220), and the removal of the `ToStrRadix` trait in favour of using the `std::fmt` functionality directly. This should make for a cleaner API, encourage less allocation, and make the implementation far more comprehensible.

The `Formatter::pad_integral` method has also been refactored make it easier to understand.

The formatting tests for integers have been moved out of `run-pass/ifmt.rs` in order to provide more immediate feedback when building using `make check-stage2-std NO_REBUILD=1`.

The benchmarks have been standardised between std::num::strconv and std::num::fmt to make it easier to compare the performance of the different implementations.

Arbitrary radixes are now easier to use in format strings. For example:

~~~
assert_eq!(format!("{:04}", radix(3, 2)), ~"0011");
~~~
Reduce reliance on `to_str_radix`

This is in preparation to remove the implementations of ToStrRadix in integers, and to remove the associated logic from `std::num::strconv`.

The parts that still need to be liberated are:

- `std::fmt::Formatter::runplural`
- `num::{bigint, complex, rational}`
auto merge of #12326 : bjz/rust/integer, r=alexcrichton

This is part of the effort to simplify `std::num`, as tracked in issue #10387.
libstd: Implement some convenience methods on vectors
auto merge of #12253 : pcwalton/rust/more-vec-ng, r=alexcrichton

r? @brson
auto merge of #12362 : liigo/rust/update-rust-manual, r=alexcrichton

change `extern mod` to `extern crate`, `package id` to `crate id`, and some lines wrapping fix, etc.
auto merge of #12382 : bjz/rust/fmt-int, r=alexcrichton

This is PR is the beginning of a complete rewrite and ultimate removal of the `std::num::strconv` module (see #6220), and the removal of the `ToStrRadix` trait in favour of using the `std::fmt` functionality directly. This should make for a cleaner API, encourage less allocation, and make the implementation more comprehensible .

The `Formatter::{pad_integral, with_padding}` methods have also been refactored make things easier to understand.

The formatting tests for integers have been moved out of `run-pass/ifmt.rs` in order to provide more immediate feedback when building using `make check-stage2-std NO_REBUILD=1`.

Arbitrary radixes are now easier to use in format strings. For example:

~~~rust
assert_eq!(format!("{:04}", radix(3, 2)), ~"0011");
~~~

The benchmarks have been standardised between `std::num::strconv` and `std::num::fmt` to make it easier to compare the performance of the different implementations.

~~~
 type | radix | std::num::strconv      | std::num::fmt
======|=======|========================|======================
 int  | bin   | 1748 ns/iter (+/- 150) | 321 ns/iter (+/- 25)
 int  | oct   |  706 ns/iter (+/- 53)  | 179 ns/iter (+/- 22)
 int  | dec   |  640 ns/iter (+/- 59)  | 207 ns/iter (+/- 10)
 int  | hex   |  637 ns/iter (+/- 77)  | 205 ns/iter (+/- 19)
 int  | 36    |  446 ns/iter (+/- 30)  | 309 ns/iter (+/- 20)
------|-------|------------------------|----------------------
 uint | bin   | 1724 ns/iter (+/- 159) | 322 ns/iter (+/- 13)
 uint | oct   |  663 ns/iter (+/- 25)  | 175 ns/iter (+/- 7)
 uint | dec   |  613 ns/iter (+/- 30)  | 186 ns/iter (+/- 6)
 uint | hex   |  519 ns/iter (+/- 44)  | 207 ns/iter (+/- 20)
 uint | 36    |  418 ns/iter (+/- 16)  | 308 ns/iter (+/- 32)
~~~
auto merge of #12411 : Arcterus/rust/time, r=alexcrichton

More work towards finishing #8784.
green: remove ancient register-saving code.

@alexcrichton said he thought this was useless (and it's old logic: it's
been there since before the runtime was written into Rust).