Move independent CSL styles into their own subdirectory

[rmzelle]

I realize changing this will likely break many downstream projects, but there would be some advantage to putting all independent CSL styles into their own subdirectory ("independent/"), as we do with the dependent CSL styles. Maybe we can make the change along with a major CSL update.

In particular, the project README is currently easily overlooked (especially for infrequent GitHub users), as visitors either have to click the README.md link or scroll all the way down the page. Considering this is our GitHub repository with the most traffic by far, that's rather unfortunate.

Smaller side benefits:

• it would separate most non-style files (like README.md, .travis.yml, renamed-styles.json, etc.) from the independent styles, making the former easier to find.
• https://github.com/citation-style-language/styles/ will likely load a little faster

[bwiernik]

Love this idea.

[rmzelle]

@bwiernik, this would be a good change to roll into the release of CSL 1.1, by the way, as that will be somewhat disruptive anyway. I'd make the change in both "master" and the "v1.1" release branch.

[bwiernik]

I agree

[bwiernik]

@adam3smith Do we want to make this change at the same time as v1.0.2 or push to CSL v1.1 whenever that may be?

[adam3smith]

Let's do this in 1.1