Added getNumOperationsInQueue() method

include/osg/OperationThread

@@ -106,6 +106,9 @@ class OSG_EXPORT OperationQueue : public Referenced
 
         /** Return true if the operation queue is empty. */
         bool empty() const { return _operations.empty(); }
+        
+        /** Return the num of pending operations that are sitting in the OperationQueue.*/
+        unsigned int getNumOperationsInQueue() const { return _operations.size(); }
 
         /** Add operation to end of OperationQueue, this will be 
           * executed by the operation thread once this operation gets to the head of the queue.*/