axis scaling anomaly

Just a little follow-up point. The normal axis autoscaling,

    > with "plot(t, s, 'b-')" commented out, doesn't take account
    > of the errorbar extrema. That is, the errorbars extend
    > beyond the autoscaled window, whereas the window should be
    > scaled to fully contain the errorbars.

Hi Gary, it turns out there were two problems here, one trivial, one
less so. The trivial problem was that we were not callling

        self.xaxis.autoscale_view()
        self.yaxis.autoscale_view()

from Axes.errorbar. That's why you saw the effect of commenting and
uncommenting the plot command.

The deeper problem was that the errorbar caps are specified in points
but the errorbars themselves are in data coords. All lines know how
to transform themselves to display, but to properly autoscale the view
lim we needed to know the cap dimensions in data coords. The fix was
to modify axes.add_line to detect the case where the line data was not
in data coords and then get the line extent in data coords by doing
line coords -> display coords -> inverse data transform -> data
coords.

The short answer is it works now and will be included in the upcoming
0.53.1 bugfix release.

JDH