The previous wording was confusing. While would we need to go through
the whole list just to find the first code point? `chars()` being an
iterator, we only need to walk from the beginning of the list.

The "nth" element can be confusing. In an array context, we know indexes
start from 0 but one may believe this is not the case with "nth". For
example, would `.nth(1)` return the first (1th/1st) or the second
element?  Rephrase a bit to be less confusing.

This is in line with other targets.

Closes rust-lang#27646

…sagew, r=alexcrichton

`FormatMessageW` always inserts trailing `\r\n` to system messages which is a minor annoyance when they're fed to `Debug` but can break formatting with `Display`.

```rust
fn main() {
    use std::env;
    if let Err(err) = env::set_current_dir("???") {
        println!("{:#?}\n{}", err, err);
    }
}
```
```_
Error {
    repr: Os {
        code: 2,
        message: "The system cannot find the file specified.\r\n"
    }
}
The system cannot find the file specified.
 (os error 2)
```

…r, r=steveklabnik

The previous wording was confusing. While would we need to go through
the whole list just to find the first code point? `chars()` being an
iterator, we only need to walk from the beginning of the list.

Note that I am not a native English speaker and I have still difficulties to spot if a "the" is needed somewhere. Feel free to take this PR as a mere suggestion.

r? @steveklabnik

…teveklabnik

The "nth" element can be confusing. In an array context, we know indexes
start from 0 but one may believe this is not the case with "nth". For
example, would `.nth(1)` return the first (1th/1st) or the second
element?  Rephrase a bit to be less confusing.

r? @steveklabnik

…arth

As title :-)
Part of rust-lang#24407.

r? @Manishearth

This is in line with other targets.

Closes rust-lang#27646