Conform to IteratorProtocol for scanning.

I've left the old callback implementations in for now, undecided whether these should be removed. The nice thing about the callback method is that it's more compact, however the logic behind it is less clear.

Sources/Examples/main.swift

@@ -11,10 +11,21 @@ catch {
 func main() throws {
     let serialPort = SerialPort(path: "/dev/cu.usbserial-0001")
     let lidar = try SwiftRPLidar(onPort: serialPort)
-    
+    var index = 0
     try lidar.iterMeasurements { measurement in
         print("Quality: ",measurement.quality, ", Angle: ", measurement.angle, ", Distance: ", measurement.distance)
-        return true
+        index += 1
+        return index <= 10
+    }
+    
+    index = 0
+    _ = try lidar.startScanning()
+    for measurement in lidar {
+        print("Quality: ",measurement.quality, ", Angle: ", measurement.angle, ", Distance: ", measurement.distance)
+        index += 1
+        if index > 10 {
+            break
+        }
     }
 }