Add robust local optical flow (RLOF) implementations (#1940)

* Add robust local optical flow (RLOF) implementations which is an improved pyramidal iterative Lucas-Kanade approach. This implementations contains interfaces for sparse optical flow for feature tracking and dense optical flow based on sparse-to-dense interpolation schemes.
Add performance and accuracy tests have been implementation as well as documentation with the related publications

* - exchange tabs with spaces
- fix optflow.bib indentation
- remove optflow_o.hpp
- change RLOFOpticalFlowParameter interfaces to Ptr<RLOFOpticalFlowParameter>
to remove error on building. Fix warnings

* introducing precompiler flag RLOD_SSE

* remove header that could not be found

* remove whitespaces
fix perf and accuracy tests

* remove x86intrin.h header

* fix ios and arm by removing last sse commands

* fix warnings for windows compilation

* fix documentation RLOFOpticalFlowParameter

* integrate cast to remove last warnings

* * add create method and function inferfaces to RLOFOpticalFlowParamter to enable python wrapper interfaces

* white space fixes / coding style

* fix perf test

* other changes: precomp.hpp / static

* use Matx44f and Vec4f instead of Mat

* normSigmas into constants

* replace ceil() calls

* maximum level is set to 5 so that it is similar value used in the papers

* implement paralellized horizontal cross segmentation as used in Geistert2016

* drop dead code

* Avoid using "data" and "step" calculations. Use .ptr<mat_type>(row, col) instead.

* Avoid using "data" and "step" calculations. Use .ptr<mat_type>(row, col) instead.

* bugfix on BEPLK with ica and adapt the accuracy tests

* more 'static' functions

* bugfix after changing ptr + step to .ptr(y,x) calls by adjusting ROI of
prevImage, currImage and derivI as well as changing the offset of the
points in the invoker classes.

* add some static_cast to avoid warning

* remove 50 grid size sample from perf test. This grid size is to sparse
for the epic interpolation

* remove notSameColor function since it is not used anymore

This patch adds ocl kernels to accelerate Dense Inverse Search
based optical flow algorithm, it acclerates 3 parts in the algorithm,
including 1) Structure tensor elements compute, 2) Patch inverse search,
3) Densification compute.

Perf and accuracy test are also added. The perf test shows it is 30%
faster than the current implementation.
Signed-off-by: Li Peng <peng.li@intel.com>

Added variational refinement as a separate class (based on implementation
inside DeepFlow, but significantly accelerated, about 4-6 times faster),
accelerated the main dense inverse search algorithm. Added several new
features including patch mean normalization for increased robustness to
illumination changes and spatial propagation, which often helps to recover
from errors introduced by the coarse-to-fine scheme. Expanded the
documentation, added new accuracy and perf tests. Refactored some of
the already existing optical flow accuracy tests.