TIVERTON, R.I. — A casino, hotel and parking garage proposed by Twin River-Tiverton LLC won final Planning Board approval Wednesday night by a 6-1 vote with two abstentions.Patti Doyle, a Twin River spokeswoman who was at the meeting, said one abstention was made because it was the member's first meeting.The casino development that is scheduled to open in 2018 is about 400 feet from the state and Fall River line.