It's sad that people have become so sensitive to a single word that great literature is controversial. In the books it isn't even in a derogatory tone, but in the context of the time it was written.
It should be pointed out that, while Mark Twain's Tom Sawyer
was first published in 1876 and Huckleberry Finn
in 1884, both novels take place in the antebellum period, circa 1840. Twain wasn't writing contemporary fiction; he was writing about an era that was already history.