Made various corrections following a quick for-loop constness audit.

Concurrency/AsyncTaskQueue.cpp

@@ -98,7 +98,7 @@ void DeferringAsyncTaskQueue::perform() {
 	std::shared_ptr<std::list<std::function<void(void)>>> deferred_tasks = deferred_tasks_;
 	deferred_tasks_.reset();
 	enqueue([deferred_tasks] {
-		for(auto &function : *deferred_tasks) {
+		for(const auto &function : *deferred_tasks) {
 			function();
 		}
 	});