Make the martial art books proper book item types.

Fixes #6589

Every item type has a use function, so call it after reading has finished.
Now martial art books can not only be read as requested in the bug, but they can also give moral, require a skill level (melee?), grant skill, require intelligence and will take a certain time to read it.

For this PR all values are copied from the playboy book (because it's the first entry in books.json). Reading takes 10 minutes, no skill/intelligence required, gives no moral, and grants no skill.