Viz initial backport, compilation fixes, moved viz/viz.hpp header according to 2.4 style
fixed documentation warnings
added guard to prevent linking VTK with Qt5
VTK off by default
rewrote perf tests for SURF
turn on CUDA part of nonfree module on Android for non-dynamic build
turn on CUDA part of stitching module on Android for non-dynamic build
update stitching sample
Merge pull request #2259 from ilya-lavrenov:ocl_surf
Merge pull request #2261 from jet47:stitching-cuda-android
Merge pull request #2178 from Nerei:viz_backport
fix path to CUDA libraries (use targets/armv7-linux-androideabi/lib)
save previous values of LOCAL_* variables and restore them at the end
Merge pull request #2274 from jet47:android-mk-fix
update test CascadeClassifier
Merge pull request #2277 from asmorkalov:android_test_path_fix
Merge pull request #2288 from asmorkalov:android_project_properties_generation_fix
Merge pull request #2285 from KonstantinMatskevich:ocl_test_cascade2.4
Multiple improvements in OpenCV examples build.

EMBED_CUDA and FORCE_EMBED_OPENCV flags added to cmake macro add_android_project;
INSTALL_CUDA_LIBRARIES option added to OpenCV.mk
opencv_dynamicuda library installation with enabled OPENCV_INSTALL_MODULES flag fixed;
CUDA initialization apportunity added to OpenCVLoader.initDebug();
Tutorial-4-CUDA sample reimplemented with static OpenCV and CUDA initialization.