The '/std/book' inheritable.

inherits: OPENABLE, READABLE
works well with: OBJ or another base class

Summary:
The 'book' inheritable implements the concept of a book which needs
to be opened before it can be read.

Functions useful for configuring:
see OPENABLE, READABLE

New Functions:
none

Overloaded Base Class Functions:
readable::read() - check if the object is open has been added.
readable::read_entry() - check if the object is open has been added.