Adds fitEllipseDirect to imgproc: The Direct least square (Direct) method by Fitzgibbon1999.

New Tests are included for the methods.
fitEllipseAMS Tests
fitEllipseDirect Tests

Comparative examples are added to fitEllipse.cpp in Samples.

Added gradiantSize param into goodFeaturesToTrack API (#9618)

* Added gradiantSize param into goodFeaturesToTrack API

Removed hardcode value 3 in goodFeaturesToTrack API, and
added new param 'gradinatSize' in this API so that user can
pass any gradiant size as 3, 5 or 7.
Signed-off-by: Vipin Anand <anand.vipin@gmail.com>
Signed-off-by: Nilaykumar Patel<nilay.nilpat@gmail.com>
Signed-off-by: Prashanth Voora <prashanthx85@gmail.com>

* fixed compilation error for java test
Signed-off-by: Vipin Anand <anand.vipin@gmail.com>

* Modifying code for previous binary compatibility and fixing other warnings

fixed ABI break issue

resolved merged conflict

compilation error fix
Signed-off-by: Vipin Anand <anand.vipin@gmail.com>
Signed-off-by: Patel, Nilaykumar K <nilay.nilpat@gmail.com>

Update planar_tracking.cpp (#9686)

Add demo code for cv::reduce, cv::merge and cv::split.

* Adds cv::resizeWindow() overload taking a single cv::Size argument.

* Replaces copied documentaion with Doxygen @overload command.

- eliminate legacy C code, used fields
- fix mutex synchronization issues
- set trackbar min/max without unnecessary truncation; allow negative values

An example program shows using cv::findHomography and cv::warpPerspective for image warping

Add constructors taking initializer_list for some of OpenCV data types (#9034)

* Add a constructor taking initializer_list for Matx

* Add a constructor taking initializer list for Mat and Mat_

* Add one more method to initialize Mat to the corresponding tutorial

* Add a note how to initialize Matx

* CV_CXX_11->CV_CXX11

Remove unnecessary Non-ASCII characters from source code (#9075)

* Remove unnecessary Non-ASCII characters from source code

Remove unnecessary Non-ASCII characters and replace them with ASCII
characters

* Remove dashes in the @param statement

Remove dashes and place single space in the @param statement to keep
coding style

* misc: more fixes for non-ASCII symbols

* misc: fix non-ASCII symbol in CMake file

*Fixing typos;
*Making codes more similar to the main one, in C++;
*Adding Grayscale option to the Python and Java codes;
*Fixing python identation, whitespaces and redundancies.