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)
Merge pull request #903 from aks2:2.4