Small improvments in XcodeCapp-Cocoa

- Do not release the Error & Warning window on close (or you can't open it again)
 - Small graphical updates
 - Remove the Growl notification in case of error (panel is sufficient)
 - Add a menu to open the error and warning panel when user wants to

Tools/xcodecapp-cocoa/AppController.m

@@ -254,13 +254,6 @@ void fsevents_callback(ConstFSEventStreamRef streamRef, void *userData, size_t n
                 }
                 else
                 {
-                    [GrowlApplicationBridge notifyWithTitle:splitedPath
-                                                description:response
-                                           notificationName:@"DefaultNotifications"
-                                                   iconData:nil
-                                                   priority:0
-                                                   isSticky:NO
-                                               clickContext:nil];                    
                     NSLog(@"Error in conversion: return message is %@", response);
                     
                     //if (![GrowlApplicationBridge isGrowlRunning])