GitLab

Flipped the include guard and the pragma, and don't use the pragma for early versions of gcc (< 3.4)

Converted indexing to std::size_t, and fixed the Node templated overloads to properly index any index type (determining what is an index type is a bit of a hack - it should be is_convertible<T, std::size_t> (I think), but I just explicitly wrote down a list)

Added emitting for a YAML::Node (instead of the ad-hoc std::ostream overload) so it'll actually emit valid YAML always

It's better organized now, I think - nodes only offer a single main way of getting the fundamental scalar (as a string), and now we can specialize a single template to read specific types.