1.0.0

This release marks the 1.0 release of regex.

While this release includes some breaking changes, most users of older versions
of the regex library should be able to migrate to 1.0 by simply bumping the
version number. The important changes are as follows:

• We adopt Rust 1.20 as the new minimum supported version of Rust for regex.
  We also tentativley adopt a policy that permits bumping the minimum supported
  version of Rust in minor version releases of regex, but no patch releases.
  That is, with respect to semver, we do not strictly consider bumping the
  minimum version of Rust to be a breaking change, but adopt a conservative
  stance as a compromise.
• Octal syntax in regular expressions has been disabled by default. This
  permits better error messages that inform users that backreferences aren't
  available. Octal syntax can be re-enabled via the corresponding option on
  RegexBuilder.
• (?-u:\B) is no longer allowed in Unicode regexes since it can match at
  invalid UTF-8 code unit boundaries. (?-u:\b) is still allowed in Unicode
  regexes.
• The From<regex_syntax::Error> impl has been removed. This formally removes
  the public dependency on regex-syntax.
• A new feature, use_std, has been added and enabled by default. Disabling
  the feature will result in a compilation error. In the future, this may
  permit us to support no_std environments (w/ alloc) in a backwards
  compatible way.

For more information and discussion, please see
1.0 release tracking issue.