Added the defaultNorm() method to the DescriptorExtractor class. This method returns the default norm type for each descriptor type. The tests and C/C++ samples were updated to get the norm type directly from the DescriptorExtractor inherited classes.
This was reported in feature report #2182 (http://code.opencv.org/issues/2182). It will make it possible to get the norm type usually applied matching method for each descriptor, instead of passing it manually.
1. Added more sync to reduction.
2. Turned off Image2D feature. Probably its support is not detected correctly.
3. Temporary disabled descriptor tests - can't localize a problem of the ocl descriptor.
