Added implementation for RGB to YUV420p color conversion
Added tests for RGB to YUV420p color conversion
Added multithreaded implementation for RGB to YUV420p color conversion
rewritten several functions from calib3d: findhomography, findfundamentalmat, findessentialmat, estimateaffine3d, computecorrespondepilines, convert points{to/from}homogeneous to C++.
reverted dangerous change in _InputArray::size()
new API for StereoMatchers
Add "build\" into .gitignore
Add implementations for Mat::zeros() and Mat::ones()

In class Mat, "static MatExpr Mat::zeros(int ndims, const int* sz, int
type)" and "static MatExpr Mat::ones(int ndims, const int* sz, int
type)" are declared but never implemented. That means we can see their
manuals from
"http://docs.opencv.org/modules/core/doc/basic_structures.html" but we
can't use them. Here I tried to finish their implementation.
I have also changed MatOp_Initializer::assign to make it support
multi-dimension Mat.
Test cases are added in test_math.cpp as well.
Remove "build/" from .gitignore
add possibility to create CUDA powered modules with ocv_define_module macro
removed preset parameter in createStereoBM, updated stereo_match sample
several minor fixes proposed by Andrey
some more minor fixes
Small changes to Python samples

    Update find_obj.py:
    Added additional error checking for the loaded files and modified the detector check to be more pythonic (is versus ==).

    Update common.py:
    Fixed a typo (contais -> contains)
reverting changes in Homography kernel function. For some reason GCC on Linux does not like it.
mask.create() re-converted to new style
Allow encoding with libx264 via ffmpeg to work

Add a call to avcodec_get_context_defaults3, this sets per-codec default values
and in the case of libx264 will stop VideoWriter::open (with fourcc=x264) from
failing due to libx264 complaining about broken ffmpeg default settings.

Set some additional libx264 encoder parameters.
Add version checks to previous modifications to ffmpeg_cap_impl.hpp

Add version checks around uses of AVCodecID and av_opt_set, since these aren't
defined for older versions of ffmpeg.
Merge pull request #617 from moshekaplan:master
Merge pull request #596 from ArtanisCV:master