Export model explanation to PDF

A client found a great deal of use from a manual PDF table we put together that contains much of the descriptions already in Koi. Having an "export model explanation to PDF" type functionality that takes all of the modeling decision data and puts it into an easily consumable table that a non-technical user can print, markup, and internalize is highly valuable.

And this is especially relevant once we have the rollup feature where the user needs to internalize decisions made for multiple models.