Clean up after review

* Disable grid lines and tick marks if x range is empty.
* Rename intervals to intervalCount when it is an integer count.
* Fix some compile warnings.

ApplicationCode/UserInterface/RiuQwtLinearScaleEngine.h

@@ -28,5 +28,5 @@
 class RiuQwtLinearScaleEngine : public QwtLinearScaleEngine
 {
 public:
-    QwtScaleDiv divideScale(double x1, double x2, double majorStepInterval, double minorStepInterval);
+    QwtScaleDiv divideScaleWithExplicitIntervals(double x1, double x2, double majorStepInterval, double minorStepInterval);
 };