simplify Qeue, update some comments and include paths

thread/scheduler.h

@@ -104,7 +104,7 @@ class Scheduler {
   Thread* active() { return dispatcher.active(); }
 
   /// \copydoc Dispatcher::isActive
-  bool isActive(const Thread* that, unsigned int* cpu = nullptr);
+  bool isActive(const Thread* thread, unsigned int* cpu = nullptr);
 
   /*! \brief Checks whether the ready queue is empty.
    *