Overhaul libraries section

[seancorfield]

Should this just defer to something else?

At a minimum, remove outdated libraries and add modern equivalents.

[seancorfield]

Library directory is going to defer to clojure-toolbox; PR in to add optional descriptions; discussing with James.

Library authoring has been overhauled/updated to use CLI (original Leiningen version preserved and linked).

[seancorfield]

Rest of library directory added to clojure-toolbox as a PR and retired from this site.

Library authoring has been well-received by the community and feedback has been incorporated.