th05/op: Declare some missing strings as such

Well, nobody actually creates perfect code the first time around, except
Linus Torvalds. (http://youtu.be/4XpnKHJAok8?t=22m18s)
th05/op: Identify Music Room strings
th05/op: Identify sound setup strings

More relocation changes?
th05/op: Identify menu description strings