Extend and test configuration-aware extended-EDN serialization.
EDN-serialize vars etc by modifying printing.

Use the letterpress library to provide tagged literal printed forms for
vars, classes, and regular expressions.  Use standard Clojure data
readers to reconstitute these forms as the appropriate values.  This
removes the need for a custom EDN reader implementation.
Merge pull request #12 from llasram/letterpress

EDN-serialize vars etc by modifying printing.