Added GIL-release code into python wrappers

Added gabor_threads.py sample

samples/python2/common.py

@@ -1,6 +1,7 @@
 import numpy as np
 import cv2
 import os
+from contextlib import contextmanager
 
 image_extensions = ['.bmp', '.jpg', '.jpeg', '.png', '.tif', '.tiff', '.pbm', '.pgm', '.ppm']
 
@@ -116,6 +117,15 @@ def nothing(*arg, **kw):
 def clock():
     return cv2.getTickCount() / cv2.getTickFrequency()
 
+@contextmanager
+def Timer(msg):
+    print msg, '...',
+    start = clock()
+    try:
+        yield
+    finally:
+        print "%.2f ms" % ((clock()-start)*1000)
+
 class RectSelector:
     def __init__(self, win, callback):
         self.win = win