Add data for Chapter 21.

Change Che Zhou's allegiance to Wei. Split Wu Shi and Wu Zilan into separate characters as in the novel (although kongming.net has them as the same person).
Correct the blurb.
Change calculation of primary faction for coappearance graphs.

Compute each character's primary faction using only on the page numbers they actually appear on.
Don't double count factions.

A person can be affiliated with the same faction on multiple different occasions as they defect back and forth. However, at least for now, we will merge each instance into a single listing per faction for display purposes.