Changing typeof(self) for MSWeakTimer* to fix a compile error for a u…

…ser since it's equivalent anyway (Fixes #6)

MSWeakTimer.m

@@ -166,7 +166,7 @@ - (void)schedule
 {
     [self resetTimerProperties];
 
-    __weak typeof(self) weakSelf = self;
+    __weak MSWeakTimer *weakSelf = self;
 
     dispatch_source_set_event_handler(self.timer, ^{
         [weakSelf timerFired];