- Patch #11947 by puregin: ensured that a book node's weight is captured when...

- Patch #11947 by puregin: ensured that a book node's weight is captured when the book node lists returned by book_location() and book_location_down() are generated. This information is required when selecting next page candidates in book_next().

Note that book_location_down() was missing an explicit field b.weight in the SQL SELECT statement, but this value would usually be supplied implicitly because it is used to ORDER the result.