If you’ve been browsing in the teen section of the library recently, you may have noticed an unusual sign: “STEAL THESE BOOKS…” it begins. But the Marin County Free Library system isn’t encouraging theft. It is trying to give patrons a chance to reads books about sensitive topics without fear, embarrassment or parental reprisal. Fairfax librarian John Elison first brought up the idea of an honor system collection in 2013, when he came to Marin…