matplotlib Code

add cla() support for spines

make default argument to Axes.get_xaxis_transform() not raise error

I made this a separate commit from the previous one because it may be
useful to see the errors that arise if get_xaxis_transform() or
get_yaxis_transform() are called with no arguments. This would allow
one to figure out which code paths are calling these methods and fix
them if needed rather than silently partially succeeding.

Arbitrary spine placement

Make polar_bar work with new Path._interpolation_steps attribute

Add *annotation_clip* attr. for text.Annotation class

a warning won't be issued for semilog axes if aspect="auto"

fixed plot_date docstring

Experimental clipping of Line _transformed_path to speed zoom and pan.

This can be modified to work with x monotonically decreasing, but
for a first try it works only with x monotonically increasing.
The intention is to greatly speed up zooming and panning into
a small segment of a very long time series (e.g., 10^6 points)
without incurring any significant speed penalty in other situations.

fixed a few bugs introduced in r7098(aspect for log-log plot).

aspect for log-log plot