Update to Part IVb (Patreon)

This is perhaps the most substantial of these updates I'll be doing; I was never quite happy with how sparse the list of surfaces felt before and now it's a lot closer to what I originally intended. As usual the alterations page includes some highlights https://worldbuildingpasta.blogspot.com/p/alterations-to-existing-posts.html but really basically everything up to the "alien skies" section has been substantially redone (with just a couple touches thereafter)