Painter: Controlling the visual features of an axis

The visual features of an axis (such as ticklengths, linewidths, distances of
the labels, their orientation, text attributes, etc.) are controlled by its
painter. You can modify these attributes by creating a painter explicitly. ...

While the axis painter has quite some parameters to adjust the output, here we
only change its width, add an arrow and alter the ticks: By default, ticks are
stroked only towards the inside of the graph (in the path examples there is no
graph but don't mind). The labels and the axis title are plotted outside of the
graph. Futhermore, the axis title (when present as in this example) is rotated
along the axis (without writing it upside down), while the tick labels are not
rotated at all.

In this example we set an `outerticklength`. Together with the
`innerticklength`, which by default is set to the same value, the ticks are
stroked across the axis. As it is common to sub-components of the axis, you
need to pass the adapted instances (stored in the variable `mypainter` here) to
the axis in its constructor.
