Add latest master (0.2.5) changes

This `PR` brings the `dev` branch up to par with the `master` in terms of core `Penthouse` functionality. The main difference is the full `@-rule handlin`, and the full functionality tests.

It was quite a job unfortunately to merge, but now all the tests succeed.

@fatso83 : Would love if you could OK this PR from your perspective before I merge into `dev, if you have time. Cheers.