Added initial pretty_print methods

[ghost]

Adds basic support for pretty printing. Currently that just means newlines and indentation (using spaces) with an options structure that can be extended in the future so pretty printing can be more sophisticated. But even this makes large JSON structures far more readable.

This starts the process of meeting the desires of issue #17, though not as extensively as requested.

[artwyman]

Closing this out after 2 years of inactivity. Feel free to re-submit a new PR if you want this feature re-considered.

[robindegen]

@artwyman For reference, What should have been done additionally to get something like this merged or even considered? Normally the pull request is created to trigger a review or at least a discussion?

[artwyman]

Sorry the experience here wasn't the best. I can't speak for what happened in 2014 when I wasn't maintainer. I closed this out as part of clearing the backlog when I took over. This repo is pretty stable and minimally maintained, though. I try to respond to new things as they come up, and merge bug-fixes, but major feature changes are subject to me or @j4cbo having the time and energy to want to engage with them.