Issue: Level 2+ Book Numbers Are Screwy

When you have a book/chapter that is at least level 2, (0. Book > 1. Book > 2. Chapter), the number scheme used to express the chapter number combined with the depth is flawed because it includes the number from previous levels once for each level past, rather than just once.

For example, the following might be in a chapter list:
1. Book
2. Book
3. Book
-- 3.1 Book Level 1
---- 3.3.1.1 Book Level 2
------ 3.3.1.1.3.3.1.1.1 Book Level 3