Major overhaul of the whole library
- No more subclasses, everything in Node.
- Node is reference counted, with copy-on-write.
- No more exceptions, toInt and friends return default values
iterator and const_iterator now returns a reference instead of a copy
Improved Node::toString
Implemented stream interface for Writer and Parser
Some compilers does not seem to like variables called "default"
Fixed accidental C++11 usage
Updated test runner