Get position for AxisLabels label and GridLines line from chart
With the introduction of the bar chart, item position - especially for the X axis - becomes a bit more tricky to determine from just width and itemCount. Instead, a method should be added to ask the chart for the centre position of a certain item, which can then be used to position the AxisLabels' label correctly below the actual item and place the GridLines based on actual item position.
Edited by Arjen Hiemstra