tracking: rework tracking API

- simplify Tracker API
- fix perf tests (don't measure video decoding)

modules/tracking/misc/python/test/test_tracking_contrib.py

@@ -0,0 +1,31 @@
+#!/usr/bin/env python
+import os
+import numpy as np
+import cv2 as cv
+
+from tests_common import NewOpenCVTests, unittest
+
+class tracking_contrib_test(NewOpenCVTests):
+
+    def test_createTracker(self):
+
+        t = cv.TrackerMIL_create()
+        t = cv.TrackerKCF_create()
+        try:
+            t = cv.TrackerGOTURN_create()
+        except cv.error as e:
+            pass  # may fail due to missing DL model files
+
+    def test_createLegacyTracker(self):
+
+        t = cv.legacy.TrackerBoosting_create()
+        t = cv.legacy.TrackerMIL_create()
+        t = cv.legacy.TrackerKCF_create()
+        t = cv.legacy.TrackerMedianFlow_create()
+        #t = cv.legacy.TrackerGOTURN_create()
+        t = cv.legacy.TrackerMOSSE_create()
+        t = cv.legacy.TrackerCSRT_create()
+
+
+if __name__ == '__main__':
+    NewOpenCVTests.bootstrap()