* a part of https://github.com/opencv/opencv/pull/11364 by Tetragramm. Rewritten and extended findNonZero & PSNR to support more types, not just 8u.
* fixed compile & doxygen warnings
* fixed small bug in findNonZero test
fixes handling of empty matrices in some functions (#11634)
* a part of PR #11416 by Yuki Takehara
* moved the empty mat check in Mat::copyTo()
* fixed some test failures
* make sure that the matrix with more than INT_MAX elements is marked as non-continuous, and thus all the pixel-wise functions process it correctly (i.e. row-by-row, not as a single row, where integer overflow may occur when computing the total number of elements)
* Issue 11242 intrinsics v_extract, v_rotate improvement, branch 3.4, without C++11 (remove type restrictions for SSE2, use PALIGNR on SSSE3, compile to no-op when imm is 0 or nlanes).
* fix whitespace
* Fix#11242 (NEON intrinsics v_rotate...) branch 3.4
Separate macro expansion OPENCV_HAL_IMPL_NEON_SHIFT_OP for bitwise shifts for integers, from macro expansion OPENCV_HAL_IMPL_NEON_ROTATE for lane rotations. Bitwise shifts do not apply to floats, but lane-rotations can apply to both.
* fix whitespace
* Fix#11242 compile error (VSX intrinsics v_rotate(a)) branch 3.4 no-c++11
* Fix CV_Asserts with negation of strings
{!"string"} causes some compilers to throw a warning.
The value of the string is not that important -- it's only for printing
the assertion message.
Replace these calls with:
CV_Error(Error::StsError, "string")
to suppress the warning.
* remove unnecessary 'break' after CV_Error()
* use universal intrinsic instead of raw intrinsic
* add 2 channels de-interleave on x86 platform
* add v_int32x4 version of v_muladd
* add accumulate version of v_dotprod based on the commit from seiko2plus on bf1852d
* remove some verify check in performance test
* avoid the out of boundary access and keep the performance
* remove unnecessary defines from vsx_utils
* fix v_load_expand, load lower 64bit
* use vec_ld, vec_st with alignment load/store on all types except 64bit
* map v_extract to v_rotate_right
* update license header
* enable VSX by default on clang since #11167
