Legend Padding option may be confusing

[jentfoo]

This issue is to track a not left at the end of PR #20. There are several ways to influence the position of the Legend. The Padding option in some cases can help provide additional space below the legend and the graph. However in the Vertical orientation it may not be applied in an expected way.

We should see if we can make this behavior more intuitive, or ideally simplify the position configuration between the Padding and the Offset.