Feature: Implement a TOML parser, conformant to the latest standards

I absolutely love zpl! I use it for every C based project, and it brings over many of the things I enjoy from C++, while also benefitting from the simplicity of C.

Would it be possible if a TOML parser could be embedded? You could take a look at [tomlc99](https://github.com/cktan/tomlc99) for reference.