[GSoC] Develop OpenCV.js DNN modules for promising web use cases together with their tutorials
* [Opencv.js doc] Init commit to add image classification example in opencv.js tutorial
* [Opencv.js doc] Make the code snippet interactive and put the functions into code snippet.
* Fix the utils.loadOpenCv for promise module
* [Opencv.js doc] Code modify and fixed layout issue.
* [Opencv.js doc] Add a JSON file to store parameters for models and show in the web page.
* [Opencv.js doc] Change let to const.
* [Opencv.js doc] Init commit to add image classification example with camera in opencv.js tutorial
* [Opencv.js doc] Init commit to add semantic segmentation example in opencv.js tutorial
* [Opencv.js doc] Add object detection example, supprot YOLOv2
* [Opencv.js doc] Support SSD model for object detection example
* [Opencv.js doc] Add fast neural style transfer example with opencv.js
* [Opencv.js doc] Add pose estimation example in opencv.js tutorial
* Delete whitespace for code check
* [Opencv.js doc] Add object detection example with camera
* [Opencv.js doc] Add json files containing model information to each example
* [Opencv.js doc] Add a js file for common function in dnn example
* [Opencv.js doc] Create single function getBlobFromImage
* [Opencv.js doc] Add url of model into webpage
* [OpenCV.js doc] Update UI for running
* [Opencv.js doc] Load dnn model by input button
* [Opencv.js doc] Fix some UI issues
* [Opencv.js doc] Change code format
Co-authored-by: Ningxin Hu <ningxin.hu@intel.com>
