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 compilation when building without the Video I/O module.
Fix incorrect size computation
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
- 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
bug fix for a crash when input image is small
Make Ctrl+S open save dialog on Windows
fix gpu sample performance test cpu part
Merge pull request #3466 from taka-no-me:ctrl_s_win
Merge pull request #3457 from burun:patch-1
Merge pull request #3464 from asuwend1:master
Merge pull request #3458 from thorikawa:kmeans-index-parallel
Merge pull request #3467 from Dikay900:fix_gpu_surf_perf_test_cpu_part
Merge pull request #3446 from pokeefe:fix-compilation-without-videoio
Merge pull request #3426 from mshabunin:doxygen-imgproc
Merge pull request #3452 from Dmitry-Me:fixIncorrectSizeComputation
Merge pull request #3428 from 23pointsNorth:patch-6