feature<App>: supports to open repository from commandline directly

src/App.xaml.cs

@@ -139,9 +139,14 @@ namespace SourceGit {
             }
 
             // Show main window
-            MainWindow = new UI.Launcher();
+            if (e.Args.Length == 1) {
+                MainWindow = new UI.Launcher(e.Args[0]);
+            } else {
+                MainWindow = new UI.Launcher(null);
+            }
             MainWindow.Show();
 
+
             // Check for update.
             if (Setting.CheckUpdate && Setting.LastCheckUpdate != DateTime.Now.DayOfYear) {
                 Setting.LastCheckUpdate = DateTime.Now.DayOfYear;

src/Git/Repository.cs

@@ -212,6 +212,8 @@ namespace SourceGit.Git {
         /// <param name="path">Local path.</param>
         /// <returns></returns>
         public static bool IsValid(string path) {
+            if (!Directory.Exists(path)) return false;
+
             var startInfo = new ProcessStartInfo();
             startInfo.FileName = App.Setting.Tools.GitExecutable;
             startInfo.Arguments = "rev-parse --git-dir";

src/UI/Launcher.xaml.cs

@@ -95,9 +95,15 @@ namespace SourceGit.UI {
         /// <summary>
         ///     Constructor
         /// </summary>
-        public Launcher() {
+        public Launcher(string path) {
             InitializeComponent();
-            NewTab(null, null);
+            if (path != null && App.IsGitConfigured && Git.Repository.IsValid(path)) {
+                var repo = App.Setting.FindRepository(path);
+                if (repo == null) repo = App.Setting.AddRepository(path, "");
+                Open(repo);
+            } else {
+                NewTab(null, null);
+            }            
         }
 
         /// <summary>