Importing the skeleton of system tray implementation and making sure it compiles and works

There was an interesting "problem" due to automatic reference counting
(-fobjc-arc flag).  XCode includes this flag by default, so making sure
that wscript is doing the same thing.
diff --git a/osx/sparkle-auto-update.mm b/osx/sparkle-auto-update.mm
index a1dc5c0..a515a79 100644
--- a/osx/sparkle-auto-update.mm
+++ b/osx/sparkle-auto-update.mm
@@ -21,7 +21,7 @@
 SparkleAutoUpdate::SparkleAutoUpdate(const char *updateUrl)
 {
   d = new Private;
-  d->updater = [[SUUpdater sharedUpdater] retain];
+  d->updater = [SUUpdater sharedUpdater];
   NSURL *url = [NSURL URLWithString: [NSString stringWithCString:updateUrl encoding:NSASCIIStringEncoding]];
   [d->updater setFeedURL: url];
   [d->updater setAutomaticallyChecksForUpdates: YES];
@@ -30,7 +30,7 @@
 
 SparkleAutoUpdate::~SparkleAutoUpdate()
 {
-  [d->updater release];
+  // [d->updater release];
   delete d;
   // presummably SUUpdater handles garbage collection
 }