Fixed variable name consistency

The function parameters were different from the ones described below.

P.S. Why is ``flow`` InputOutputArray, shouldn't it be just OutputArray? If so, shouldn't the reason be specified - e.g. so others can benefit as well (e.g. not allocating memory on every frame?)
Documenting imgproc module

- disabled doxygen tree
- enabled doxygen enum listing
- added imgproc reference to main page
- enabled BiB support
- chenged doxygen root page format
Fix anchor for small symmetrical column filters.

In the unoptimized version of small symmetrical column filters, when we
try to detect if the kernel, ky, is equal to [1;2;1] or [1;-2;1] we
should take into consideration that the anchor points in the middle
element.
Remove redundant -mfpu=neon flag.

This flag is already added in line 131.
Merge pull request #3436 from oresths:compiler_option
Merge pull request #3435 from oresths:filter_anchor_fix
Merge branch 'master' of https://github.com/Itseez/opencv.git
Fix compilation when building without the Video I/O module.
Optimize pyrUp_unrolled() by mad function.

It could improve performance when image size is large.
E.g. OCL_PyrUpFixture_PyrUp.PyrUp/18
Fix incorrect size computation
Updated Documentation (HoughCircles)

Rewrite the note on HoughCircles documentation to make it more clear

Add note to clarify that the output vector of found circles is sorted by
descending order of centres accumulator values.

Also delete reductant lines on the HoughCircles documentation.

Added comments to hough circles function.

Added comments to icvhoughgradient

Misalignment in line 1183 corrected
Update py_colorspaces.rst

mask = cv2.inRange(hsv, lower_green, upper_green)
to
mask = cv2.inRange(hsv, lower_blue, upper_blue)
Parallize building kmeans index in flann
Merge pull request #3451 from wangyan42164:ocl_pyrup_unrolled
Merge branch 'master' of https://github.com/Itseez/opencv.git
- Use cv::Mutex to safely update converged flag
- Use cv::AutoBuffer rather than new allocation
- Fix "assignment operator could not be generated" warning
Fix "assignment operator could not be generated" warnings
samples: gpu: fix include of TickMeter
bug fix for a crash when input image is small
Make Ctrl+S open save dialog on Windows