* 1. for cross platform, use cv::CommandLineParser instead of getopt.h
2. use cv::glob to search folder instead of dirent.h
3. fix some other warnings of function from cstdlib
4. add some const and some auto

* 1. fix some other warnings of function from cstdlib
2. add some const and some auto
3. i forgot...

* switch quantize tools default on

* check OpenCV first, if not found, disable quantize tools

* add _CRT_SECURE_NO_DEPRECATE for msvc and remove *_s functions

* add _CRT_SECURE_NO_DEPRECATE for msvc and remove *_s functions

* keep the one line style block

* folding bracket

* dynamic_cast -> static_cast

* fix compile error of yolov3detectionoutput layer

* fix ncnn2table coredump when [Input] layer not found in ncnn.param

* fix onnx2ncnn MemoryData dims problem #1330

* fix ncnn2int8 bug (see #1336)

* fix bug that MemoryData as multi operations input

* fix ncnn2table find_blob_index_by_name data failed bug, see #1338

* fix ncnn2table find_blob_index_by_name data failed bug, see #1338, fix change requested

* Update CMakeLists.txt

enable quant

* fix opencv compatibility issue with major higher than 2

* initial the ncnn post training quantization tools

* clear some comments of tools

* fix the Travis ci compiler error