Fix issue with solvePnPRansac and Nx3 1-channel input when the number of points is 5. Try to uniform the input shape of projectPoints and undistortPoints.

Lab, Luv and XYZ conversions rewritten to wide intrinsics (#14106)

* rgb2xyz<float> re-vectorized

* rgb2xyz_i vectorized for ushort and uchar

* xyz2rgb<float> vectorized

* xyz2rgb_i vectorized for both uchar and ushort

* intermediate conversions (int->float) rewritten

* packed rgb2luv rewritten

* (some) float conversions rewritten

* burnt volatile int _3 and similar

* RGB2Lab_b rewritten

* tests: logging made better

* RGB2Lab_f (LRGB path) rewritten

* Lab2RGBfloat rewritten

* Lab2RGBinteger and Lab2RGB_b rewritten to wide universal intrinsics

* Luv2RGBinteger wide vectorized

* RGB2Lab_b fixed: v_sub_wrap instead of saturated sub

* warnings fixed

* trying to fix compilation on older compilers

* using 16x8 registers for 8-element dot product

* cleanup added

* splineInterpolate: loop unrolled, perf fix for f32x4

* Lab2RGBfloat: grab 2x more data to process on f32x4

* nrepeats for Luv2RGBfloat, +20% perf

* minor

* nrepeats to RGB2Lab_f

* Lab2RGBinteger: no tab for linear BGR

* nrepeats for RGB2Luvfloat

* Luv2RGBinteger: no tab for linear RGB

* +10% more to perf of Luv2RGBfloat

* nrepeats for 256-simd for Lab2RGBfloat

* less warnings

* BOM removed

* CV_SIMD_WIDTH used for lanes number checking

* trilinearPackedInterpolate: 128-bit specialization added

* fix build; no vx_cleanup(), instrumentation instead

* added support for Eigen cross-compilation

* cmake: fix Eigen detection

Add SOLVEPNP_IPPE for planar pose estimation. Add solvePnPGeneric function that returns all the pose solutions and the reprojection errors.

* Fix typo: 'divisble' -> 'divisible'

* Fix typo: 'One of arguments' -> 'One of the arguments'

Extend optical flow tutorial (#14314)

* extend python optical flow tutorial with cpp example code and add it to general tutorial directory

* remove unused parameters, fix comparison between signed and unsigned int

* fix hsv range problem

* switch to samples::findFile for sample file location

* switch to command line parameter for path

* remove old tutorial as in 14393

* minor fixes

Extend meanshift tutorial (#14393)

* copy original tutorial and python code

* add cpp code, fix python code

* add camshift cpp code, fix bug in meanshift code

* add description to ToC page

* fix shadowing previous local declaration

* fix grammar: with -> within

* docs: remove content of old py_meanshift tutorial, add link

* docs: replace meanshift tutorial subpage in Python tutorials

* switch to ref to fix wrong breadcrumb navigation

* switch to cmdline for path as in #14314

* Apply suggestions from code review

* order programming languages alphabetically

- moved code into separate file due issue with handling of CMake policies