Provide a lowest permissible interval time to effects and limit the update rate of selected effects

include/effectengine/Effect.h

@@ -103,4 +103,6 @@ private:
 	QImage          _image;
 	QPainter       *_painter;
 	QVector<QImage> _imageStack;
+
+	double	_lowestUpdateIntervalInSeconds;
 };

include/effectengine/EffectModule.h

@@ -51,4 +51,5 @@ public:
 	static PyObject* wrapImageCOffset          (PyObject *self, PyObject *args);
 	static PyObject* wrapImageCShear           (PyObject *self, PyObject *args);
 	static PyObject* wrapImageResetT           (PyObject *self, PyObject *args);
+	static PyObject* wrapLowestUpdateInterval  (PyObject* self, PyObject* args);
 };