revert to 16x16 rooms as that covers standard bitsy as well as bitsy hd

src/room.rs

@@ -137,8 +137,7 @@ impl Room {
         let mut exits = String::new();
         let mut endings = String::new();
 
-        let sqrt = (self.tiles.len() as f64).sqrt() as usize; // 8 for SD, 16 for HD
-        for line in self.tiles.chunks(sqrt) {
+        for line in self.tiles.chunks(16) {
             for tile in line {
                 tiles.push_str(tile);
                 if room_format == RoomFormat::CommaSeparated {