Migration to https://github.com/citation-style-language/journals

[rmzelle]

I just created a new repository, journals, to hold the journal metadata originally maintained in "utilities/generate_dependent_styles", and migrated the files and their git history using "git subtree split", as documented at https://makingsoftware.wordpress.com/2013/02/16/using-git-subtrees-for-repository-separation/.

@adam3smith, @zuphilip, please don't commit or make PRs to "utilities/generate_dependent_styles" anymore. Once I correct the style generation script in "journals" to deal with the new directory structure, and confirm everything works, I plan to delete "utilities/generate_dependent_styles" to complete the migration.

[adam3smith]

OK, thanks