Merge branch 'master' into 68000Mk2

Concurrency/AsyncTaskQueue.cpp

@@ -103,3 +103,8 @@ void DeferringAsyncTaskQueue::perform() {
 		}
 	});
 }
+
+void DeferringAsyncTaskQueue::flush() {
+	perform();
+	AsyncTaskQueue::flush();
+}

Concurrency/AsyncTaskQueue.hpp

@@ -87,6 +87,11 @@ class DeferringAsyncTaskQueue: public AsyncTaskQueue {
 		*/
 		void perform();
 
+		/*!
+			Blocks the caller until all previously-enqueud functions have completed.
+		*/
+		void flush();
+
 	private:
 		// TODO: this is a shared_ptr because of the issues capturing moveables in C++11;
 		// switch to a unique_ptr if/when adapting to C++14