Possible fix for issue #4, using JSON references.
Undo a bit of distracting reformatting that my IDE decided was necessary.
Remove println and fix up some more whitespace.
Add tests for list, map, and multi-object cycles (and make them pass).
Removed dependence on thread-local storage, introduced visitor context.
Some refactoring of visitor context.
Whoops, remove some debug code that got left in.
Have Visitor.setVisitorContext() return self to make chainable.
Also add .idea directory to .gitignore.
Merge pull request #42 from balthorium/possible-fix-for-issue-4-plus-description

Possible fix for issue 4 plus description