Precis-i18n

- Release 1.0 version.
- Add test that all codepoints are idempotent.
- Update copyright year (2018).

- (IMPORTANT) This version changes the results of the CaseMapped
profiles due to publication of new RFC\'s.
- The CaseMapped profiles now default to using ToLower instead of
CaseFold.
- Added profile variants for CaseFold, just for completeness.
- Update references to RFC numbers in documentation and comments.

- (IMPORTANT) This version changes the results of the Nickname
profile.
- Add support for proposed changes to RFC 7564 that will make the
Nickname profile idempotent (Issue 3).
- Add the \"DISALLOWED/not_idempotent\" error message.
- Sign pypi package with gpg.

- (API CHANGE) Profile\'s `enforce` method now returns a Unicode
string instead of UTF-8 bytes. This API change affects code that
uses get_profile() to obtain a profile. The codec still returns
UTF-8 bytes. (Issue 2)
- The codec search function now returns None when it doesn\'t find a
matching codec.

- Add LICENSE.txt and CHANGELOG.md to source tarball. (Issue 1)
- Update travis and pypi metadata for Python 3.6.

- Improve error messages when a string is disallowed.
- Clean up test examples. Add a few more test cases.