libd1394 2.x support for mingw on windows added
libd1394 2.x support for mingw on windows added
Merge branch 'mingw-libdc1394-2-windows' of https://github.com/dominikrose/opencv into mingw-libdc1394-2-windows
Merge branch 'mingw-libdc1394-2-windows' of https://github.com/dominikrose/opencv into mingw-libdc1394-2-windows
Merge branch 'mingw-libdc1394-2-windows' of https://github.com/dominikrose/opencv into mingw-libdc1394-2-windows
Merge branch 'mingw-libdc1394-2-windows' of https://github.com/dominikrose/opencv into mingw-libdc1394-2-windows
Merge branch 'mingw-libdc1394-2-windows' of https://github.com/dominikrose/opencv into mingw-libdc1394-2-windows
libdc1394 - removed validation for msvc compiler in CMakeLists.txt
Bug #2967, basic_structures.rst, fix 2 typos
Bug #2967, void DescriptorMatcher::radiusMatch() // description unclear,
only file:  common_interfaces_of_descriptor_matchers.rst
Bug #2966, insert CV_Assert(size.width>0 && size.height>0); in imshow()
(tab to space) 2x
(typo)
[3rd attempt] fixed HOGDescriptor::detectMultiScale() to group weights as well as ROIs
Reverted back to the previous method where a public method groupRectangles was added to HOGDescriptor to take care of ROI and weight grouping
Added spacing in a nested template argument list.
Replace the pull request guidelines with a link to the wiki.

I've moved the contents of CONTRIBUTING.md to the wiki (and slightly
expanded it), so the former is no longer required. I've put a link to the
wiki page and a summary in the README.
fixed some gpu tests (different rounding results due to float arithmetics)
a few fixes of ocl::perf test cases
Fix ocl::pyrup kernel build on Mac.