message: add more safety to smart_refctd_ptr
diff: @@ -280,6 +280,12 @@ namespace core
  return *this;
  }
  + // so that you don't mix refcounting methods
  + void grab() = delete;
  + void grab() const = delete;
  + bool drop() = delete;
  + bool drop() const = delete;
  +
  inline I_REFERENCE_COUNTED* get() const { return ptr; }
  inline I_REFERENCE_COUNTED* operator->() { return ptr; }
  