Printer should also support pretty-printed output

[bpsm]

Currently Printer produces output that is all in one line:

[{:a "asdfasdfasdfasdfasdfasdf" :b 1234 :c "uoiuojoijoijmoinoihohkjhlkjhlkjhu", :d #{ … } … } … ]

This is great for communication, since it's compact and no human has to be able to read it. On the other hand, it stinks for debugging scenarios or where edn data is stored in version control where it may be subject to merges.

Printer should support the option to format output in multiple lines with some amount of indentation to indicate logical nesting. It need not be highly configurable. It need not match the output of Clojure's pprint. It must be faster than Clojure's pprint.

[bpsm]

Done. See:
428da65