Added cv2.boxPoints() functionality to Python bindings (Feature #2023)

http://www.code.opencv.org/issues/2023

eg:

In [3]: box = ((10,10),(5,5),0)

In [4]: cv2.boxPoints(box)
Out[4]:
array([[  7.5,  12.5],
       [  7.5,   7.5],
       [ 12.5,   7.5],
       [ 12.5,  12.5]], dtype=float32)

modules/imgproc/include/opencv2/imgproc.hpp

@@ -1318,6 +1318,9 @@ CV_EXPORTS_W double contourArea( InputArray contour, bool oriented = false );
 //! computes the minimal rotated rectangle for a set of points
 CV_EXPORTS_W RotatedRect minAreaRect( InputArray points );
 
+//! computes boxpoints
+CV_EXPORTS_W void boxPoints(RotatedRect box, OutputArray points);
+
 //! computes the minimal enclosing circle for a set of points
 CV_EXPORTS_W void minEnclosingCircle( InputArray points,
                                       CV_OUT Point2f& center, CV_OUT float& radius );

modules/imgproc/src/rotcalipers.cpp

@@ -398,3 +398,10 @@ cvMinAreaRect2( const CvArr* array, CvMemStorage* /*storage*/ )
     return (CvBox2D)rr;
 }
 
+void cv::boxPoints(cv::RotatedRect box, OutputArray _pts)
+{
+    _pts.create(4, 2, CV_32F);
+    Mat pts = _pts.getMat();
+    box.points((Point2f*)pts.data);
+}
+