Added support to open file when double clicked in explorer.

ucalc/MainWindow.xaml.cs

@@ -24,7 +24,12 @@ namespace UCalc
         {
             base.OnContentRendered(e);
 
-            if (_showRecover)
+            var args = Environment.GetCommandLineArgs();
+            if (args.Length > 1)
+            {
+                OpenBilling(args[1]);
+            }
+            else if (_showRecover)
             {
                 _showRecover = false;
 
@@ -46,7 +51,7 @@ namespace UCalc
 
         private void OnNewClick(object sender, RoutedEventArgs e)
         {
-            var newWindow = new NewWindow {Owner = this};
+            var newWindow = new NewWindow { Owner = this };
 
             if (newWindow.ShowDialog() == true)
             {
@@ -63,7 +68,7 @@ namespace UCalc
             }
             else
             {
-                var button = (Button) sender;
+                var button = (Button)sender;
                 var contextMenu = button.ContextMenu;
                 // ReSharper disable once PossibleNullReferenceException
                 contextMenu.PlacementTarget = button;
@@ -76,7 +81,7 @@ namespace UCalc
 
         private void OnOpenFromDiskClick(object sender, RoutedEventArgs e)
         {
-            var dialog = new OpenFileDialog {Filter = "MietRechner Datei (*.mr) | *.mr"};
+            var dialog = new OpenFileDialog { Filter = "MietRechner Datei (*.mr) | *.mr" };
 
             if (dialog.ShowDialog() == true)
             {
@@ -91,7 +96,7 @@ namespace UCalc
 
         private void OnOpenRecentClick(object sender, RoutedEventArgs e)
         {
-            var recentlyOpenedItem = (RecentlyOpenedItem) ((MenuItem) sender).DataContext;
+            var recentlyOpenedItem = (RecentlyOpenedItem)((MenuItem)sender).DataContext;
 
             OpenBilling(recentlyOpenedItem.Path);
         }