.tight_layout.auto_adjust_subplotpars can return None now if the new
subplotparams will collapse axes to zero width or height. This prevents
tight_layout from being executed. Similarly
.tight_layout.get_tight_layout_figure will return None.
To improve import (startup) time, private modules are now imported lazily. These modules are no longer available at these locations:
- matplotlib.backends.backend_agg._png
- matplotlib.contour._contour
- matplotlib.image._png
- matplotlib.mathtext._png
- matplotlib.testing.compare._png
- matplotlib.texmanager._png
- matplotlib.tri.triangulation._tri
- matplotlib.tri.triangulation._qhull
- matplotlib.tri.tricontour._tri
- matplotlib.tri.trifinder._tri