A little bit more for #55
And a light move for empty classes and IDs from errors to advices.
Adds tests folder to gitignore
Titles are handled better when quoted
Fix anchors links

same as here https://github.com/trulia/hologram-example/pull/24
Merge pull request #76 from a5e/hologram

Hologram
Improvements next to #73
Deletes duplicates in navigation

I wonder why this was needed in the hologram-example :/
Merge pull request #77 from a5e/fix-nav

Deletes duplicates in navigation
Wondering too :D Another navigation, I didn't look in details their example.
Improving layout table criterias
Thanks to @olamedia in #74, I was able to make those criterias a lot more explicits.
New fix for #74
With better explnations come better fixes :D
Errors are now documented.
First step for #55.
Beginning warnings for #55
Some tests are improved but still have to be tested.
Close #79
Thanks to @HugoGiraudel for seeing this !
Close #80
Removing a test case searching for label not directly followed by a form field.
The rule is that they should be visually associated, but that's not referring to the DOM.
This test was not relevantat all.
Adding some docs for #55
Litlle bit more for #55
Fixing a few things
First, self-closing tags' messages could override another message in an adjacent tag because it used ::before too.
Now self-closing tags'messages are added on ::after, and any adjacent tag which halready has a message can carry two messages.

Another issue was about sectionning tags, the test case was too hard. <article> can be in a <section>, for example.