fix TrackerKCF.Update crash

[t-yuki]

Related to #459 but another problem, I caught OpenCvSharp.OpenCVException from OpenCvSharp.Tracking.Tracker.Update method with TrackerKCF that was created with custom tracker parameter.

OpenCvSharp.OpenCVException: type == (((6) & ((1 << 3) - 1)) + (((2)-1) << 3))
 OpenCvSharp.NativeMethods.<>c.<.cctor>b__1581_0(ErrorCode status, String funcName, String errMsg, String fileName, Int32 line, IntPtr userdata)
 OpenCvSharp.NativeMethods.tracking_Tracker_update(IntPtr obj, IntPtr image, Rect2d& boundingBox)
 OpenCvSharp.Tracking.Tracker.Update(Mat image, Rect2d& boundingBox)

It was not happened on openCVSharp 3.3.1.20171117 but after upgrade to 3.4.1.20180319, that method always throw exceptions.

After several investigations, I found that TrackerKCF.Params struct has mismatched layout.
Layout attribute [MarshalAs(UnmanagedType.Bool)] means marshal as BOOL, which is actually int in Win32, but the corresponding struct field in OpenCV was bool.
So let's use UnmanagedType.U1.

[shimat]

Sorry for the late reply🙇‍♀️Thanks!