Initial Windows RT support commit.
GPU module turned off;
TIFF support turned off;
Windows Managment and Video IO (VFW) turned off.
Multiple Windows RT fixes

TIFF build was fixed;
Direct Show back-end was enabled;
More accurate guards implemented.
More accurate guards for WinRT features in CMake.
Highgui tests for GUI disabled for WinRT;
Warnings fix;
Multiple fixes for WinRT

Fixed flann build with NEON;
Fixed Haming distance with NEON;
Honest cvRound for WinRT added;
cvRound test added;
Video IO with direct show disabled;
Video IO tests turned off for ARM WinRT.
HAVE_WIN32UI and HAVE_VFW checks and defines added.
Perf tests for Video IO on WInRT fixed.
Update Android toolchain to the latest version supporting NDK r8e
disabled perf tests for gpu VideoWriter and VideoReader
Experimental MS Media Foundation API support added
Add ocl::stereobp function.

OpenCL StereoBeliefPropagation, ported from GPU implementation.
fixed SparseMat Iterator compilation error (bug #2921)
Fix some build errors.
Fix compilation errors.
fixed compilation warning for CUDA files

command line option '-Wsign-promo' is valid for C++/ObjC++ but not for C [enabled by default]
Native activity install fixed.
Code review notes fixed.
Merge pull request #728 from taka-no-me:ndk-r8e
Merge pull request #738 from jet47:gpu-disable-videoenc-test