Racial injustice, coming of age, and the love of fathers are just some of the themes explored in the current Cumming Playhouse show. Off Broadway Productions began a seven-day run Friday of the Southern classic, “To Kill a Mockingbird.” The novel by Harper Lee is also being featured in this year’s Forsyth Reads Together, a program of the Forsyth library system that promotes community-wide reading and literary enrichment.