Improve restoring layout when RestoreOption_RelativeToMainWindow is used

Doesn't make much sense to apply a scalling factor to the floating window's
position. Instead we should apply the factor to the delta position between
the main window and the floating window

Fixes #171

src/LayoutSaver.cpp

@@ -995,8 +995,7 @@ void LayoutSaver::ScalingInfo::translatePos(QPoint &pt) const
 
 void LayoutSaver::ScalingInfo::applyFactorsTo(QPoint &pt) const
 {
-    pt.setX(qCeil(pt.x() * widthFactor));
-    pt.setY(qCeil(pt.y() * heightFactor));
+    translatePos(pt);
 }
 
 void LayoutSaver::ScalingInfo::applyFactorsTo(QSize &sz) const