relicense shootout-regex-dna.rs

Part of #14248

The authors are @pcwalton and @BurntSushi, and we have their agreement.
update identifier naming warnings to give an example

This updates identifier warnings such as ``struct `foo_bar` should have a
camel case identifier`` to provide an example.

Closes #14738.
Add visit_attribute to Visitor, use it for unused_attribute

The lint was missing a *lot* of cases previously.
Remove the attribute_usage lint

It has been superseded by the unused_attribute lint.

[breaking change]
Improve error message for range in match

Range allows char and numeric types, but previous error message
mentioned only numeric types.
Add back hint for crate level attributes
Remove unused name_str_pair method
auto merge of #14743 : Sawyer47/rust/range-msg, r=huonw

Range allows char and numeric types, but previous error message
mentioned only numeric types.
std::io: expand the oneshot/periodic docs.

Examples!

Fixes #14714.
auto merge of #14728 : TeXitoi/rust/relicense-shootout-regex-dna, r=brson

Part of #14248

The authors are @pcwalton and @BurntSushi, and we have their agreement.

@brson OK?
auto merge of #14741 : sfackler/rust/visit-attr, r=alexcrichton

The lint was missing a *lot* of cases previously.
Add detection of dead struct fields
Remove the dead code identified by the new lint
auto merge of #14745 : huonw/rust/timer-doc, r=alexcrichton

std::io: expand the oneshot/periodic docs.

Examples!

Fixes #14714.
Implement Hash for Bitv and BitvSet

Closes #14744
auto merge of #14749 : sfackler/rust/bitv-hash, r=alexcrichton

Closes #14744
Fix spelling errors in comments.
Fix an LLVM assertion when matching against static strings

Fixes #8315
Fixes #11940
Remove a redundant bitcast from fail!() handling
auto merge of #14751 : jbcrail/rust/fix-comments, r=alexcrichton