FileDownload - a library downloading file from breakpoint

It's used for downloading http file with C++. You can resume downloading from last break point. I have referred https://github.com/junyux/HttpClient and re-wrapped it. Pass testing in windows and ubuntu.

api: FileDownload\FileDownload\include\downloadAPI.h

demo: D:\src\FileDownload\test\main.cpp

std::shared_ptr<talFD::IDownloadFile> p1 = std::shared_ptr<talFD::IDownloadFile>(talFD::get_interface());
talFD::errorCode ec;
ec = p1->initialize(url1, savedir, progress_func);
if (ec != talFD::errorCode::initialize_finish)

{

    printf("Initilize error: %d\n", ec);
 	return -1;
}
p1->start_download();