Integrate string of source into :publics

[martinklepsch]

Currently publics contain the name, docstring, type, line and perhaps other things. For direct inlining of source strings it would be useful if it would also contain a :source field with a string.

clojure.repl/source-fn may work on the Clojure platform but probably not for ClojureScript. Also someone mentioned to me that source-fn may have issues specifically with double-colon keywords like ::foo/bar.

Making this work would also be a useful contribution to the overall efforts of cljdoc.