Page metadata

[alterae]

Templates should have access to more information about the current page than just its content. They should be able to see any custom data defined in that page (see #7), as well as probably the path to the page and any children (see #4).

It would probably make sense to stick all this data under a page variable structured like so:

[page]
path = "path/to/page.html"
data = {} # hashmap of metadata defined in the page
children = [] # array of child pages
content = "" # page content 

This will probably rewrite significant refactoring, the implementation of some kind of page struct, and a way to do frontmatters. Child pages might also necessitate path normalization.