r? @Manishearth

 Right now it's all hosted over GitHub pages so https doesn't work, so only link
to the http version.

 `str`s is messy but string is incorrect.

 This did not render as intended:

>This is defined in RFC 5737 - 192.0.2.0/24 (TEST-NET-1) - 198.51.100.0/24 (TEST-NET-2) - 203.0.113.0/24 (TEST-NET-3)

vs.

> This is defined in RFC 5737
- 192.0.2.0/24 (TEST-NET-1)
- 198.51.100.0/24 (TEST-NET-2)
- 203.0.113.0/24 (TEST-NET-3)

 I corrected several spelling errors in the external documentation.

 Correct pretty-printing of `type Foo<T> where T: Bound = ...;`

Fix #25031

 This commit does two things: it adds an example for indexing vectors, and it changes the \"Examples\" section to use full sentences.

This change was spurred by someone in the #rust IRC channel asking if there was a `.set()` method for changing the `i`-th value of a vector (they had missed that `Vec` implements `IndexMut`, which is easy to do if you're not aware of that trait).

 This script used to be used to [extract the grammar sections from the reference](https://github.com/rust-lang/rust/pull/8585), but there is [now a separate src/doc/grammar.md](https://github.com/rust-lang/rust/pull/22308) that generates grammar.html where the grammar sections that used to be in the reference live, so there is no longer a need to extract the grammar from the reference.

I ❤ deleting code :) But I totally understand if there's a reason to keep this around that I don't know about :)

 These all had a typo where they were accessing the seconds field, not the
nanoseconds field.

 Sweeten the two main HashMap/HashSet examples from [here](http://doc.rust-lang.org/std/collections/struct.HashMap.html) and [here](http://doc.rust-lang.org/std/collections/struct.HashSet.html) with some deref and loop sugar.

(I've only tested this using [this playpen][1].)

[1]: https://play.rust-lang.org/?code=fn%20main()%20%7B%0A%20%20%20%20use%20std%3A%3Acollections%3A%3AHashMap%3B%0A%20%20%20%20%0A%20%20%20%20%2F%2F%20type%20inference%20lets%20us%20omit%20an%20explicit%20type%20signature%20(which%0A%20%20%20%20%2F%2F%20would%20be%20%60HashMap%3C%26str%2C%20%26str%3E%60%20in%20this%20example).%0A%20%20%20%20let%20mut%20book_reviews%20%3D%20HashMap%3A%3Anew()%3B%0A%20%20%20%20%0A%20%20%20%20%2F%2F%20review%20some%20books.%0A%20%20%20%20book_reviews.insert(%22Adventures%20of%20Huckleberry%20Finn%22%2C%20%20%20%20%22My%20favorite%20book.%22)%3B%0A%20%20%20%20book_reviews.insert(%22Grimms%27%20Fairy%20Tales%22%2C%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%22Masterpiece.%22)%3B%0A%20%20%20%20book_reviews.insert(%22Pride%20and%20Prejudice%22%2C%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%22Very%20enjoyable.%22)%3B%0A%20%20%20%20book_reviews.insert(%22The%20Adventures%20of%20Sherlock%20Holmes%22%2C%20%22Eye%20lyked%20it%20alot.%22)%3B%0A%20%20%20%20%0A%20%20%20%20%2F%2F%20check%20for%20a%20specific%20one.%0A%20%20%20%20if%20!book_reviews.contains_key(%26(%22Les%20Mis%C3%A9rables%22))%20%7B%0A%20%20%20%20%20%20%20%20println!(%22We%27ve%20got%20%7B%7D%20reviews%2C%20but%20Les%20Mis%C3%A9rables%20ain%27t%20one.%22%2C%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20book_reviews.len())%3B%0A%20%20%20%20%7D%0A%20%20%20%20%0A%20%20%20%20%2F%2F%20oops%2C%20this%20review%20has%20a%20lot%20of%20spelling%20mistakes%2C%20let%27s%20delete%20it.%0A%20%20%20%20book_reviews.remove(%26(%22The%20Adventures%20of%20Sherlock%20Holmes%22))%3B%0A%20%20%20%20%0A%20%20%20%20%2F%2F%20look%20up%20the%20values%20associated%20with%20some%20keys.%0A%20%20%20%20let%20to_find%20%3D%20%5B%22Pride%20and%20Prejudice%22%2C%20%22Alice%27s%20Adventure%20in%20Wonderland%22%5D%3B%0A%20%20%20%20for%20book%20in%20to_find.iter()%20%7B%0A%20%20%20%20%20%20%20%20match%20book_reviews.get(book)%20%7B%0A%20%20%20%20%20%20%20%20%20%20%20%20Some(review)%20%3D%3E%20println!(%22%7B%7D%3A%20%7B%7D%22%2C%20*book%2C%20*review)%2C%0A%20%20%20%20%20%20%20%20%20%20%20%20None%20%3D%3E%20println!(%22%7B%7D%20is%20unreviewed.%22%2C%20*book)%0A%20%20%20%20%20%20%20%20%7D%0A%20%20%20%20%7D%0A%20%20%20%20%0A%20%20%20%20%2F%2F%20iterate%20over%20everything.%0A%20%20%20%20for%20(book%2C%20review)%20in%20book_reviews.iter()%20%7B%0A%20%20%20%20%20%20%20%20println!(%22%7B%7D%3A%20%5C%22%7B%7D%5C%22%22%2C%20*book%2C%20*review)%3B%0A%20%20%20%20%7D%0A%20%20%20%20%0A%7D

 - `File::open` is for opening a file in read-only mode
- `File::create` is for opening a file in write-only mode, which is what we want instead for this example to make sense

This makes the `bit::vec::bench::bench_bit_vec_big_union` benchmark go
from `774 ns/iter (+/- 190)` to `602 ns/iter (+/- 5)`.

(There's room for more work here too: if one can guarantee 128-bit
alignment for the vector, the compiler actually optimises `union`,
`intersection` etc. to SIMD instructions, which end up being ~5x faster
that the original version, and 4x faster than the optimised version in
this patch.)

Right now it's all hosted over GitHub pages so https doesn't work, so only link
to the http version.

strs messy but string is something else...

This was one last spot where directories were being leaked through with
arguments of the form `\\?\` which neither `ld.exe` nor `gcc.exe` does
understands so the prefix needed to be stripped.

Closes #25072

This was one last spot where directories were being leaked through with
arguments of the form `\\?\` which neither `ld.exe` nor `gcc.exe` does
understands so the prefix needed to be stripped.

Closes #25072

Add several regression tests and remove some unnecessary FIXMEs.

These all had a typo where they were accessing the seconds field, not the
nanoseconds field.

I'm uncertain whether the 3 implementations in `net2` should unwrap the socket address values. Without unwrapping it looks like this:

```
UdpSocket { addr: Ok(V4(127.0.0.1:34354)), inner: 3 }
TcpListener { addr: Ok(V4(127.0.0.1:9123)), inner: 4 }
TcpStream { addr: Ok(V4(127.0.0.1:9123)), peer: Ok(V4(127.0.0.1:58360)), inner: 5 }
```

One issue is that you can create, e.g. `UdpSocket`s with bad addresses, which means you can't just unwrap in the implementation:

```
#![feature(from_raw_os)]
use std::net::UdpSocket;
use std::os::unix::io::FromRawFd;

let sock: UdpSocket = unsafe { FromRawFd::from_raw_fd(-1) };
println!("{:?}", sock); // prints "UdpSocket { addr: Err(Error { repr: Os(9) }), inner: -1 }"

```

Fixes #23134.

This makes the `bit::vec::bench::bench_bit_vec_big_union` benchmark go
from `774 ns/iter (+/- 190)` to `602 ns/iter (+/- 5)`.

(There's room for more work here too: if one can guarantee 128-bit
alignment for the vector, the compiler actually optimises `union`,
`intersection` etc. to SIMD instructions, which end up being ~5x faster
that the original version, and 4x faster than the optimised version in
this patch.)

- I found n error in the book, before contributing the patch to fix it, I had to find where they were hosted
- It took me quite look to find where within the rust-lang *organisation* it was! ... and this should make it easier for the next person in the same position

Fix #25031

Without the inline annotation this:
    str::from_utf8_unchecked( slice::from_raw_parts( ptr, len ) )
doesn't get inlined which can be pretty brutal performance-wise
when used in an inner loop of a low level string manipulation method.

This changes the std::vec module docs to use full sentences. It also adds an example
for indexing vectors.

Override methods `count`, `last`, and `nth` in vec::IntoIter.

#24214