Add method KeypointBasedMotionEstimator::estimate(InputArray, InputArray) to support both cpu & opencl algorithm processing

the orignal estimate function has input parameters defined as "Mat", this prevent users to call into algorithm opencl path

Check file name only:
    Excluding from source files list (optimization is disabled):
    C:/Code/SrcExt/OpenCV/Buildv3.2_x64/modules/core/opencl_kernels_core.cpp

New p3p algorithm (accepted by CVPR 2017) (#8301)

* add p3p source code

* indent 4

* update publication info

* fix filename

* interface done

* plug in done, test needed

* debugging

* for test

* a working version

* clean p3p code

* test

* test

* fix warning, blank line

* apply patch from @catree

* add reference info

* namespace, indent 4

* static solveQuartic

* put small functions to anonymous namespace

Same as https://github.com/opencv/opencv/pull/8525/commits/9210cefb36868e201f7e0c8b84e4ee4f91b5432b but for this file too.