Changes to bookcases. Made them visually more appealing, and made them b...

This commit includes revamped sprites and connected book cases, which basically work just like counters or tables. They connect If a bookcase is to its left/right. If someone wants to code it, go right ahead.

For reference:
http://i.imgur.com/yv7bhlE.png
http://i.imgur.com/RrlKVTx.png

Bottom right is the one we have now. (default)

Signed-off-by: Pewtershmitz <xengan@gmail.com>