add support for c++? like add the demo of c++. about opencv_zoo

[fengyuentau]

After an internal discussion on this feature, we agree that C++ demos can be added but they should be clean and simple enough to show how to run inference and get the expected output. I will create an issue tracking the status of C++ demos and I will provide the first C++ demo as soon as possible.

[fengyuentau]

The first C++ demo is here: #138. Feel free to review.

[fengyuentau]

It could be interesting. Currently our demos are focusing on easy-to-use and work-out-of-the-box. Demos in C++ could be helpful in some cases but not the first priority to consider.

[kekxv]

It could be interesting. Currently our demos are focusing on easy-to-use and work-out-of-the-box. Demos in C++ could be helpful in some cases but not the first priority to consider.

python is too concise, and it is difficult to convert to other languages.

[fengyuentau]

Task tracker for adding C++ demos: #135.