Reorganization

[tsackton]

Merge reorganization branch into main:

• Move NPCs and PCs to a shared People directory
• Move Gods, Religion, and Multiverse to a shared Cosmology directory
• Create a Time directory with, so far, just Holidays and Festivals.
• Move Vehicles and Items into an unshared Things directory; specific Items can be shared as desired.
• Update .gitignore to share everything except: a DM directory for planning notes, etc; Things; Campaigns