Reorganize Sift_Distance.py

* Put Shift_Distance code into sift_distance function
* Add import statements for numpy and opencv

src/Sift_Distance.py

@@ -1,4 +1,9 @@
-sift = cv.xfeatures2d.SIFT_create()
+import numpy as np
+import cv2
+
+
+def sift_distance():
+    sift = cv2.xfeatures2d.SIFT_create()
     original_kp, original_des = sift.detectAndCompute(left,None)
     new_kp, new_des = sift.detectAndCompute(right,None)
 
@@ -21,4 +26,3 @@ z2 = np.array([[complex(c[0],c[1]) for c in pts2]])
 
     # Distance between featured matched keypoints
     FM_dist = abs(z2 - z1)
-