Support for core Book module

> Please open another issue for book support if you think it's worth following up. It's not on my timeline at the moment...

done

> (from the same post) As for 'book' - I don't use that much myself, but just had a look at its data structure. I'm not sure of a way to make child pages attach to their parents unless I know the parents ID. We'd have to do string matching of some sort which can be unreliable, especially with autogenerated content.
If solved, it can be plugged in OK, but the algorithm to find the appropriate parent would have to be worked on. It would look a lot like the code that currently knits pages into the menu tree. (I think book.module is now a special version of menu.module?) The real problem is that each insertion is independent of the other, and not every page has it's parent available at all times.
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My workflow is fairly common, so other users may have some input. I think the string matching may be reliable - I can assign attributes to my content such that each task has a unique identifier. I have to do that at some point anyway. If every page had a unique identifier, then maybe concatenating them would show the book structure.
The good part about the Book module is that it permits comments, and it permits child pages and sub-children. This way I can have a hierarchical setup similar to my print and PDF docs for familiarity, along with commentability and searchability for my Support guys.
So in the end, a guy can:
1. Go to (for example) the Backup and Restore section,
2. Explore the child pages and select Restore from Encrypted Backup,
3. Review that procedure.
4. Add comments about a tricky part a customer ran into
5. Use the Print/PDF/Email module to email me the comment so I am sure to include it in the next revision
6. use the same feature to notify other Support guys about the tricky part.

It would be truly excellent to have support for the Books module!