Drop Python2 support.

samples/python/gaussian_mix.py

@@ -1,13 +1,5 @@
 #!/usr/bin/env python
 
-# Python 2/3 compatibility
-from __future__ import print_function
-import sys
-PY3 = sys.version_info[0] == 3
-
-if PY3:
-    xrange = range
-
 import numpy as np
 import cv2 as cv
 
@@ -16,7 +8,7 @@ from numpy import random
 def make_gaussians(cluster_n, img_size):
     points = []
     ref_distrs = []
-    for _i in xrange(cluster_n):
+    for _i in range(cluster_n):
         mean = (0.1 + 0.8*random.rand(2)) * img_size
         a = (random.rand(2, 2)-0.5)*img_size*0.1
         cov = np.dot(a.T, a) + img_size*0.05*np.eye(2)