1.2.3 -- 20 June 2017
- Requesting an unknown comparator (e.g. Comparator.nonexisting) no longer throws
  but returns undefined.

1.2.2 -- 14 June 2017
- Removed all ES2105 language features (let, const, rest, arrow-functions, etc)
  because a lot of tooling still only supports ES5
- Fixed mistake in naturalSort initialisation

1.2.1 -- 14 June 2017
- '__esModule' Babel support (returns undefined instead of throw 'unknown comparator')
- Made 'use strict' local
- Small change to documentation

1.2.0 -- 13 June 2017
- Fixed 'main' field in package.json
- Refactoring & cleanup
- keyMappers extension target removed
- Extensions are now all mapped to the 'steps' target
- Added 'orElse' and 'end' step
- No braces now also supported on configurable steps (althought 'end' is required if last step)

1.1.1 -- 8 June 2017
- Small doc change for markdown-spec differences between viewers

1.1.0 -- 8 June 2017
- Added ascending & descending result mappers
- Added 'locale' comparator that uses String.localeCompare
- Fixed small mistakes in the documentation

1.0.0 -- 5 June 2017
- Initial version