New feature: check if upgrade available on github

FileLiberator/UNTESTED/DownloadFile.cs

@@ -0,0 +1,35 @@
+using System;
+using System.Net.Http;
+using System.Threading.Tasks;
+using Dinah.Core.Net.Http;
+
+namespace FileLiberator
+{
+	// frustratingly copy pasta from DownloadableBase and DownloadPdf
+	public class DownloadFile : IDownloadable
+	{
+		public event EventHandler<string> DownloadBegin;
+		public event EventHandler<DownloadProgress> DownloadProgressChanged;
+		public event EventHandler<string> DownloadCompleted;
+
+		public async Task<string> PerformDownloadFileAsync(string downloadUrl, string proposedDownloadFilePath)
+		{
+			var client = new HttpClient();
+
+			var progress = new Progress<DownloadProgress>();
+			progress.ProgressChanged += (_, e) => DownloadProgressChanged?.Invoke(this, e);
+
+			DownloadBegin?.Invoke(this, proposedDownloadFilePath);
+
+			try
+			{
+				var actualDownloadedFilePath = await client.DownloadFileAsync(downloadUrl, proposedDownloadFilePath, progress);
+				return actualDownloadedFilePath;
+			}
+			finally
+			{
+				DownloadCompleted?.Invoke(this, proposedDownloadFilePath);
+			}
+		}
+	}
+}