Neopolengine Categories

Send the full set of categories for every files so the template can choose which one to use

Generate categories so logic can be applied in the engine and the template can just render (something to be looked at later if optimization seems necessary)

Identify what position files are in different categories so previous/next links can be generated.

Setup previous/next links for each page. Logic for that will start in the code and then check to see if there's an easy way to move to a config

Would have to encode logic to decide how prev/next works if a page is in multiple categories

Could actually apply previous/next based off template, e.g. if it's a `neodocs`` file the prev next comes from a list dedicated to that.

Would want a flag to prevent files from showing up in a category list (e.g. the home pages) Or, maybe the idea would be to split out to a different template? That's probably easier to deal with.

Feels like using the `-- type`` attribute as the base makes the most sense.

Could get fancy later and do something like setting a cookie or query string if someone hits a page from a category listing and then dynamically switch the prev/next to be in that category instead of the overall type.

That would deal with multiple categories too.

Consider setting up an explicit order config. For example, to setup the first N number of pages in the `neodocs`` then let the rest of them filter in? Or, would the list just be explicit? probably the later