Completing the document-based app setup.

Multiple repositories can now be opened by using the File → Open… menu option.
Each document is a PBGitRepository with a PBDetailController controlling the window. PBRepositoryDocumentController is the document controller.
When launched, the application will attempt to open a repository with the current directory as its path. If this fails it will display an open panel to allow the user to select one.

PBRepositoryDocumentController.m

@@ -0,0 +1,21 @@
+//
+//  PBRepositoryDocumentController.mm
+//  GitX
+//
+//  Created by Ciarán Walsh on 15/08/2008.
+//  Copyright 2008 __MyCompanyName__. All rights reserved.
+//
+
+#import "PBRepositoryDocumentController.h"
+
+
+@implementation PBRepositoryDocumentController
+// This method is overridden to configure the open panel to only allow
+// selection of directories
+- (NSInteger)runModalOpenPanel:(NSOpenPanel *)openPanel forTypes:(NSArray *)extensions
+{
+	[openPanel setCanChooseFiles:NO];
+	[openPanel setCanChooseDirectories:YES];
+	return [openPanel runModalForDirectory:nil file:nil types:nil];
+}
+@end