[2916753] Wrong API signature- yscale
workaround for a regression in PyQt4-4.6.{0,1}
Fix bug in Line2D from last commit: restore full recache in unit chane callback
Line2D: simplify set_data functionality; recache only a coord. that was set.
fix whitespace, one docstring in lines.py
pyplot.spy should set current image only if it is making an image
Fix cmap data for gist_earth_r, etc.
Add docs for new features in mathtext
zorder support in figure: use same sort idiom as in axes
spines and ticks: implement smart bounds
