Merge branch 'master' into gpu-cuda-rename

Conflicts:
	modules/core/include/opencv2/core/cuda.hpp
	modules/cudacodec/src/thread.cpp
	modules/cudacodec/src/thread.hpp
	modules/superres/perf/perf_superres.cpp
	modules/superres/src/btv_l1_cuda.cpp
	modules/superres/src/optical_flow.cpp
	modules/videostab/src/global_motion.cpp
	modules/videostab/src/inpainting.cpp
	samples/cpp/stitching_detailed.cpp
	samples/cpp/videostab.cpp
	samples/gpu/stereo_multi.cpp

samples/cpp/generic_descriptor_match.cpp

@@ -33,7 +33,7 @@ int main(int argc, char** argv)
     std::string params_filename = std::string(argv[4]);
 
     Ptr<GenericDescriptorMatcher> descriptorMatcher = GenericDescriptorMatcher::create(alg_name, params_filename);
-    if( descriptorMatcher.empty() )
+    if( !descriptorMatcher )
     {
         printf ("Cannot create descriptor\n");
         return 0;