Added some classes from a stackoverflow to utilize Qt's concurrency functions especially cancellable QFuture's

core/TaskExecutor.h

@@ -0,0 +1,32 @@
+#ifndef TASKEXECUTOR_H
+#define TASKEXECUTOR_H
+/* From answer by Hatter
+ *
+ * https://stackoverflow.com/questions/5423058/qfuture-that-can-be-cancelled-and-report-progress
+ */
+#include "ControllableTask.h"
+#include "RunControllableTask.h"
+
+/**
+ * @brief The TaskExecutor class
+ *
+ * The user should sublass ControllableTask, implement background routine which checks sometimes
+ * method shouldRun() of TaskControl instance passed to run(TaskControl&) and then use it like:
+ *
+ * QFututre<int> futureValue = TaskExecutor::run(new SomeControllableTask(inputForThatTask));
+ *
+ * Then she may cancel it by calling futureValue.cancel(), bearing in mind that cancellation is
+ * graceful and not immediate.
+ *
+ */
+class TaskExecutor {
+public:
+	template <class T>
+	static QFuture<T> run(ControllableTask<T>* task) {
+		return (new RunControllableTask<T>(task))->start();
+	}
+};
+
+
+
+#endif // TASKEXECUTOR_H