Feature allows to exclude CUDA or OpenCL optimizations at all even CUDA is used
on build. Exclusion of CUDA or OpenCL cut unwanted dependencies.

fixed doc builder warnings; make sure the tests give reasonable results when OpenCL is not available

fixing issues from coverity scan 1167937, 1167938, 1167939, 1127248 (http://scan.coverity.com/projects/169?tab=Overview)

Inlining and customizing sampling functions to reduce memory traffic and compute
Improve calcOrientation implementation.
Using more efficient rounding routines.
Removing unnecessary use of local memory

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.