Make the plot and handle movement stick to an 'Grid'

Make the plot and the handle stick to a grid, the
grid is defined by the integers in the rulers, so
a time of 10,2 is converted to 10, and will put the
point at 10.

Signed-off-by: Tomaz Canabrava <tcanabrava@kde.org>

qt-ui/diveplanner.h

@@ -51,11 +51,11 @@ protected:
 
     void clear_generated_deco();
 	void create_deco_stop();
-	bool isPointOutOfBoundaries(QPointF point);
+	bool isPointOutOfBoundaries(const QPointF& point);
 
 private:
 
-    void moveActiveHandler(QPointF pos);
+    void moveActiveHandler(const QPointF& pos);
 	QList<QGraphicsLineItem*> lines;
 	QList<DiveHandler *> handles;
 	QGraphicsLineItem *verticalLine;