Also moved to a non-static approach, and added a high-level class to
allow easy access to all other entity queries, for use in mixed-entity
scenarios and easier/simpler injection.
For book, shelves and chapters.
Made much of the existing handling generic to entity types.
Added new MixedEntityListLoader to help load lists somewhat efficiently.
Only manually tested so far.
Rolled out HTML editor field and store logic across all target entity
types. Cleaned up WYSIWYG input logic and design.
Cleaned up some injected classes while there.
