* export SVM::trainAuto to python #7224

* workaround for ABI compatibility of SVM::trainAuto

* add parameter comments to new SVM::trainAuto function

* Export ParamGrid member variables

Warping a matrix with more than 4 channels using BORDER_CONSTANT and
INTER_NEAREST, INTER_CUBIC or INTER_LANCZOS4 interpolation led to
undefined behaviour. This commit changes the behavior of these methods
to be similar to that of INTER_LINEAR. Changed the scope of some of the
variables to more local. Modified some tests to be able to detect the
error described.

#resolves: 7881

remove printf statement and associated variables from invMapPointSpherical() in undistort.cpp

* Improve documentation.

* Update imgproc.hpp

Implement cv::cuda::calcHist with mask support (#8367)

* Implement cuda::calcHist with mask

* Fix documentation build warning

* Have their own step sizes for src and mask. Fix review comment.

3.2 version doesn't support 4 channel color image
detections, unlike 3.1. Now, we don't call
CV_Error() if 4 channel image is given.

resolve #8326