FFMpegView - Import Script for WebWorker

[mdhsl]

The current version of the view allows to use webworker. If so, a webWorker is created from the view and use the FFMpeg.js library to decode the frame.
The problem is that we need to load the script directly from the webworker:

 initFFMPEG_DECODER_WORKER: function (callback) {
        console.log("init FFMPEG worker");
        var blobURL = URL.createObjectURL(new Blob(['(',
                function () {
                    //TODO
                    importScripts("http://opensensorhub.github.io/osh-js/Toolkit/vendor/ffmpeg/ffmpeg-h264.js");
                    // register all compiled codecs
                    Module.ccall('avcodec_register_all');
                    ...

This is the big problem and we have to find a way to load the script in a different way.