Neopolitan: gref Section

For global references

The only thing it has is the `-> gref`neo` tag and an `>> id`neo` attribute.

The id attribute is used to pull the details of a reference from another location (that's TBD on how that will work. It might be a set of pages with just the references, or possible it'll just have the ability to reach into any page.

I'm not worried about id collisions, I'll just edit anything that collides.