No Axis Label Position Support

[rjack1201]

There is currently now support for Axis Label Position (chxp). This becomes important if you want to do custom axis labels to describe the whole axis. For instance, if you had a chart that had 1000 to 10000 dollars on the y-axis and the years 2000 to 2010 on the x-axis, you would like to add a overall labels of "Dollars" and "Years" on each respective axis. chxp is needed to position the labels into the middle of the axis. The google documentation can be found on this page:

https://developers.google.com/chart/image/docs/chart_params#axis_label_positions

Does adding this make sense?