Long before she was doused with water, the Wicked Witch was a smart and misunderstood green gal — at least according to author Gregory Maguire. “Wicked’’ is the award-winning prequel (for anyone who has been in a cave for 15 years) about the two witches of Oz. Sept. 1 at 7:30 p.m. ( through Oct. 17). $38-$103 (VIP tickets start ...