Add support for Clojure's reader macros

[dcostaras]

Summary of Changes

Clojure has a number of reader macros, some of which have differing syntax to other lisps. This PR adds support for the unique reader macros.

Public Domain Dedication

• [x] In contributing, I relinquish any copyright claims on my contribution and freely release it into the public domain in the simple hope that it will provide value.

[dcostaras]

@countvajhula I'm unsure if the Clojure interface file is the best place for Clojure specific functionality?

[dcostaras]

And a second question re. process is; would you rather small PRs that focused on say one reader macro or one PR for all of Clojure's reader macros?

[countvajhula]

@dcostaras Probably one PR for all of them (the existing PRs are fine). And yeah the clojure interface file is a good place for it.

[countvajhula]

Would love to see some before / after examples to get a sense of what we're going for. Something like what's in the description for this issue.