Support for known limitations

Documentation & code quality release.

This release focuses on redocumenting this package,
improving code quality, test coverage and CI automation.

Code quality patch:

* code modernization & relinting
* enhanced CI checks & automation
* more tests, including testable examples
* introduced first fuzz test

Merge pull request #59 from fredbi/chore/perf-minor-optimizations

perf: minor performance optimization for escape/unescape

deps: removed (indirect) dependency to mailru/easyjson

fixes #53

Signed-off-by: Frederic BIDON <fredbi@yahoo.com>