Wrong namespace for OpenCV 3.2

[kneczaj]

When compiling with OpenCV 3.2 I had a problem that cv::SIFT cannot be found. The following patch fixes it.

diff --git a/SM/include/mtf/SM/FeatureTracker.h b/SM/include/mtf/SM/FeatureTracker.h
index 93b04b6..a19c89a 100644
--- a/SM/include/mtf/SM/FeatureTracker.h
+++ b/SM/include/mtf/SM/FeatureTracker.h
@@ -104,7 +104,7 @@ public:
        typedef FLANNCVParams FLANNParams;
 #endif
        //typedef std::unique_ptr<cv::Feature2D> Feature2DPtr;
-       typedef std::unique_ptr<cv::SIFT> SIFTPtr;
+       typedef std::unique_ptr<cv::xfeatures2d::SIFT> SIFTPtr;^M

        FeatureTracker(
                const ParamType *grid_params = nullptr,

[abhineet123]

fixed in commit b150223bd461e50cef691da691457d472c191b7c