fixed shared CPDocumentController instantiation and added its test

Tests/Manual/CPDocumentControllerTest/AppController.j

@@ -0,0 +1,38 @@
+/*
+ * AppController.j
+ * CappDoc
+ *
+ * Created by You on May 24, 2012.
+ * Copyright 2012, Your Company All rights reserved.
+ */
+
+@import <Foundation/CPObject.j>
+@import "Document.j"
+@import "DocumentController.j"
+
+@implementation AppController : CPObject
+{
+    CPDocumentController subclassedCPDocumentController;
+}
+
+- (void)applicationDidFinishLaunching:(CPNotification)aNotification
+{
+    // This is called when the application is done loading.
+    var cpAlert = [CPAlert alertWithMessageText:@"Is this the shared instance? " + ([CPDocumentController sharedDocumentController] == subclassedCPDocumentController) defaultButton:@"OK" alternateButton:nil otherButton:nil informativeTextWithFormat:nil];
+    [cpAlert beginSheetModalForWindow:[[CPApplication sharedApplication] mainWindow]];
+}
+
+- (void)applicationWillFinishLaunching:(CPNotification)aNotification
+{
+    // instantiate a subclass of DocumentController
+    subclassedCPDocumentController = [[DocumentController alloc] init];
+}
+
+- (void)awakeFromCib
+{
+    // This is called when the cib is done loading.
+    // You can implement this method on any object instantiated from a Cib.
+    // It's a useful hook for setting up current UI values, and other things.
+}
+
+@end