* Change `utf8` variable names to `non_ascii` to be more clear, since
ASCII and UTF-8 are compatible.

* Fix `EscapeDefault` struct description to follow the typical iterator
method format with a link to the generating function.

* Add more `escape_default` examples to cover every case mentioned in
the function description itself.

This commit stabilizes the `#![windows_subsystem]` attribute which is a
conservative exposure of the `/SUBSYSTEM` linker flag on Widnows platforms. This
is useful for creating applications as well as console programs.

Closes rust-lang#37499

fixed some clippy warnings in libcollections

Some markdown fixes, a few readability improvements, but mostly trivial stuff.

…ystem, r=aturon

rustc: Stabilize the `#![windows_subsystem]` attribute

This commit stabilizes the `#![windows_subsystem]` attribute which is a
conservative exposure of the `/SUBSYSTEM` linker flag on Widnows platforms. This
is useful for creating applications as well as console programs.

Closes rust-lang#37499

… r=alexcrichton

Add a note about overflow for fetch_add/fetch_sub

Fixes rust-lang#40916

r? @steveklabnik

Improve some docs for VecDeque

r? @GuillaumeGomez

API Docs: ascii

Add/update docs for the `ascii` module per rust-lang#29341.

r? @steveklabnik

…xcrichton

Added links to from_utf8 methods in Utf8Error

Referencing  rust-lang#29375. Linked the `from_utf8` methods for both `String` and `str` in the description. Also linked the `u8` to its documentation

…teveklabnik

Added links to types in from_utf8 description

References rust-lang#29375. Link to types mentioned in the documentation for `from_utf8` (`str`, `&[u8`], etc). Paragraphs were reformatted to keep any one line from being excessively long, but are otherwise unchanged.

Improve documentation for `std::fs::DirBuilder`