Merge pull request #692 from vpisarev:refactor_calib3d_stereo

diff --cc modules/calib3d/src/stereobm.cpp
Simple merge

diff --cc modules/calib3d/test/test_stereomatching.cpp
Simple merge

diff --cc modules/gpu/perf/perf_calib3d.cpp
Simple merge

diff --cc modules/python/src2/cv2.cpp
index 33f8e9e,78cd96e..eb72301
--- 1/modules/python/src2/cv2.cpp
--- 2/modules/python/src2/cv2.cpp
+++ b/modules/python/src2/cv2.cpp
@@@ -126,11 -128,11 +126,15 @@@ typedef Ptr<FeatureDetector> Ptr_Featur
  typedef Ptr<DescriptorExtractor> Ptr_DescriptorExtractor;
  typedef Ptr<Feature2D> Ptr_Feature2D;
  typedef Ptr<DescriptorMatcher> Ptr_DescriptorMatcher;
 +typedef Ptr<BackgroundSubtractor> Ptr_BackgroundSubtractor;
 +typedef Ptr<BackgroundSubtractorMOG> Ptr_BackgroundSubtractorMOG;
 +typedef Ptr<BackgroundSubtractorMOG2> Ptr_BackgroundSubtractorMOG2;
 +typedef Ptr<BackgroundSubtractorGMG> Ptr_BackgroundSubtractorGMG;
  
+ typedef Ptr<StereoMatcher> Ptr_StereoMatcher;
+ typedef Ptr<StereoBM> Ptr_StereoBM;
+ typedef Ptr<StereoSGBM> Ptr_StereoSGBM;
+ 
  typedef Ptr<cv::softcascade::ChannelFeatureBuilder> Ptr_ChannelFeatureBuilder;
  
  typedef SimpleBlobDetector::Params SimpleBlobDetector_Params;