Merge lp://staging/~julien-spautz/cable/markup-refactor-and-better-urls into lp://staging/cable

What kind of URLs didn't work before?

google.com doesn't work, http://google.com does

> google.com doesn't work, http://google.com does

google.com probably should work, as it would highlight a lot of non URLs.

AFAIK there were some problems with more exotic URLs. Valadoc URLs were only partially highlighted because they contained a '!' (I fixed it, but probably introduced some other bugs in the process, because I don't even understand our current regex, which is never a good thing...).

The new regexes are a little more sophisticated and should match URLs more accurately. Also there's no point in maintaining two different implementations, so using the same as pantheon terminal will benefit both projects.

I'll also add a bunch of unit test to make sure we don't break existing behaviour in case we decide to modify the regexes.

s/should/shouldn't/

Typing bug 1234 in #vala on GimpNet should result in a bot posting a red link. Instead, the markup is visible

All unit tests pass

So it seems to work in certain channels, like #test and #vala.

Seems like other channels disabled it, if that's possible.

Except for the new regexes, the behaviour of the code didn't change, so if something doesn't work, it's not a regression but a bug in the original implementation, which should be fixed in a separate branch anyway.