Modified type of variables float64 to int32 in Rect.msg

[iory]

OpenCv's types of Rect.x, Rect.y, Rect.height, Rect.width are int. so, we should use int32. http://docs.opencv.org/2.4/modules/core/doc/basic_structures.html

For your convenience, the Rect<> alias is available: typedef Rect Rect;