Fix deprecated use of ~
Remove outdated info about nested block comments. Fixes #14767
Removed doubled wording.

The guide previously stated:

> The compiler will automatically convert a box box point to a reference like &amp;point.

This fixes the doubled word `box`, so the statement reads

> The compiler will automatically convert a box point to a reference like &amp;point.

The code it is referring to is `compute_distance(&on_the_stack, on_the_heap);`, so a single `box` is appropriate.
Update description to reflect language changes

Previously, the type system's restrictions on borrowing were summarized as

> The previous example showed that the type system forbids any borrowing of owned boxes found in aliasable, mutable memory

This did not jive with the example, which allowed mutations so long as the borrowed reference had been returned. Also, the language has changed to no longer allow aliasable mutable locations. This changes the summary to read

> The previous example showed that the type system forbids mutations of owned boxed values while they are being borrowed. In general, the type system also forbids borrowing a value as mutable if it is already being borrowed - either as a mutable reference or an immutable one.

This adds more general information for the experienced reader as well, to offer a more complete understanding.
sync: Once is no longer unsafe, update docs
Show impl for Ref & RefMut
Fix unclear wording of comment
emacs: do not highlight `#foo]` as an attribute

part of #14347
emacs: highlight `#[foo = "bar"]` attributes

Setting `OVERRIDE` to `t` overrides the conflicting highlight Emacs
places on string literals.

Fix #14347
librustc: Forbid identifiers that shadow in the same pattern in let
bindings and function arguments.

Issue #14581.

To fix code that this breaks, give the pattern identifiers different names.

[breaking-change]
rustc: Remove ~[T] from the language

The following features have been removed

* box [a, b, c]
* ~[a, b, c]
* box [a, ..N]
* ~[a, ..N]
* ~[T] (as a type)
* deprecated_owned_vector lint

All users of ~[T] should move to using Vec<T> instead.
auto merge of #14703 : alexcrichton/rust/no-more-owned-vectors, r=brson

The following features have been removed

* `box [a, b, c]`
* `~[a, b, c]`
* `box [a, ..N]`
* `~[a, ..N]`
* `~[T]` (as a type)
* deprecated_owned_vector lint

All users of ~[T] should move to using Vec<T> instead.
std: Remove i18n/l10n from format!

* The select/plural methods from format strings are removed
* The # character no longer needs to be escaped
* The \-based escapes have been removed
* '{{' is now an escape for '{'
* '}}' is now an escape for '}'

Closes #14810
[breaking-change]
Improve docs and refactore std::os.
auto merge of #14713 : darnuria/rust/Improve_std_os_documentation_#2, r=alexcrichton

Improving documentation, consistency, removes evils empty lines etc...
auto merge of #14799 : mcreinhard/rust/tilde-fix, r=alexcrichton

Replaced `~Drawable` with `Box<Drawable>` in tutorial
mk: Allow usage of a local jemalloc install

This adds a new configure option, --jemalloc-root, which will specify a location
at which libjemalloc_pic.a must live. This library is then used for the build
triple as the jemalloc library to link.
travis: Use a pre-installed jemalloc
mk: Allow using a locally compiled libuv.a

Closes #5563
auto merge of #14792 : alexcrichton/rust/local-jemalloc, r=brson

This configures the makefiles to copy a local jemalloc/libuv library into place instead of building the local copy of one. Additionally, this switches our travis builds to using the system-provided jemalloc instead of a custom-built jemalloc to exercise this functionality.