- differ from 3.4 branch

* Remove TensorFlow and protobuf dependencies from object detection scripts

* Create text graphs for TensorFlow object detection networks from sample

Multi-argument CV_Assert() is accessible via CV_Assert_N() (with malformed messages).

remove from DNN module headers

Enable Torch layers tests with Intel's Inference Engine backend.

Remove some assertions

Replace std::ifstream to std::istream

Add test for new importer

Remove constructor to load file

Rename cfgStream and darknetModelStream to ifile

Add error notification to inform pathname to user

Use FileStorage instead of std::istream

Use FileNode instead of FileStorage

Fix typo

* Added ResizeBilinear op for tf

Combined ResizeNearestNeighbor and ResizeBilinear layers into Resize (with an interpolation param).

Minor changes to tf_importer and resize layer to save some code lines

Minor changes in init.cpp

Minor changes in tf_importer.cpp

* Replaced implementation of a custom ResizeBilinear layer to all layers

* Use Mat::ptr. Replace interpolation flags

* Update Intel's Inference Engine deep learning backend

* Remove cpu_extension dependency

* Update Darknet accuracy tests

to avoid accessing of 'p[-1]' (static code analysers dislike this)

replaced to cv::error()

* Custom deep learning layers support

* Stack custom deep learning layers

Enable FP16 GPU target for DL Inference Engine backend.

include relu6 ocl kernel and layer fusion support
Signed-off-by: Li Peng <peng.li@intel.com>