Lemoncheesecake

- **API**: add the ability to perform a check within a hook (before/after suite, before/after all tests)
- **API / Report**: add a outcome flag for hooks
- **API**: improve default step description ("-" has been replaced by the current context description)
- **Console reporting**: add the ability display only the current testsuite id instead of the full testsuite path

- **HTML report**: fix regressions introduced in 0.3.3
- **Checkers**: minor fixes and improvements
- **Compatibility**: make it work (again) with Python 3
- **Console reporting**: fix minor issue dealing with terminal width and long test id / test steps
- **Unit tests**: add tests for for `lemoncheesecake.checkers`

- **HTML report**: escape all the data coming from the JSON report
- **HTML report**: do not display a testsuite header if the testsuite does not contain tests directly
- **Console reporting**: optimize the output depending on the terminal size
- Fix missing check details for some checkers

- **Reporting**: Rework the report dir creation so that the rotation mechanism also works on Windows

- **API**: multiple workers can now be used
- **API**: worker's hooks execution is now performed within the reporting session context (logs, attachments, etc... can be used in hooks)

- Improve `is_Nxx` matcher descriptions (for instance `is between 200 and 299` becomes `is 2xx`)
- Improve the way the content-type hint is displayed in request & response bodies
- Fix wrong URL formatting when the `params` argument contains multivalued parameters (simply use the full URL already
computed by requests through `PreparedRequest`)
- Drop Python 3.6 support