WebClient-based download clients for common file hosts targeting .NET Framework 4.0.

Usage is very similar to that of WebClient:

using(IFileHostDownloadClient client = new FileHostDownloadClient()) {

	client.DownloadProgressChanged  = (sender, e) => {
		Console.WriteLine("Download progress: "   e.ProgressPercentage);
	};

	client.DownloadFileCompleted  = (sender, e) => {
		Console.WriteLine("Download complete!");
	};

	Uri address = new Uri("https://drive.google.com/open?id=0BwmD_VLjROrfTHk4NFg2SndKcjQ");
	string filename = client.GetFilename(address);

	client.DownloadFileAsync(address, filename);

	// ...

}

FileHostDownloadClient acts a generic client that spawns specialized clients when required/available.

DropboxDownloadClient and GoogleDriveDownloadClient are registered by default, and additional clients can be registered via FileHostDownloadClient.RegisterClient.

DropboxDownloadClient specializes in downloading files from Dropbox, and accepts both share links and direct download links. It is able to follow through Dropbox's "speedbump" page (a verification page that appears when downloading certain file types) automatically.

GoogleDriveDownloadClient specializes in downloading files from Google Drive, and accepts both share links and direct download links. It is able to follow through Google Drive's "can't scan this file for viruses" automatically for files that are large enough to trigger it.

Additional implementations can be created by inheriting from FileHostDownloadClientBase and then registered for use on specific domains via FileHostDownloadClient.RegisterClient.