book covers and new bookshelves

covers of enchanted books should differ in color (similar to potions). also, depending on the level of enchantment, there may be a different number of gold stripes on the spine of the book. new bookshelves should not fill and empty by default. The player himself has the right to choose where to put which book. also, do not make bookcases (old and new) only from oak. they should fit into any interior.