To make bbox_inches='tight' work correctly, we cache the positions ofall of the axes, change their aspect to 'auto', adjust the transformson the figure, render the output, and then restore the previoussetting of aspect to each of the figures.  This prevent the Axes fromtrying to adjust their size on draw. This matters because for therender that is emitted the figure transforms are out of sync with thefigure size.As part of cleaning fixing the rendering of Axes3D inmatplotlib#8896 /matplotlib#16472we started to use apply_aspect to re-size the area the Axes3D takes upto maintain a fixed ratio between the axes when the aspect is "auto".However this conflicts with the expectation in tight_bbox.adjust_bboxas it assumes setting the aspect to "auto" will prevent any axesresizing.This commit addresses this by: - exiting the Axes3D.apply_aspect early if aspect is auto - adding a new aspect mode 'auto_pb' which is the default   for Axes3D which maintains the current master branch behavior   of maintaining a fixed ratio between the sizes of the x, y z axis   independent of the data limits. - re implement several functions on Axes3D to make sure they handle   sharez correctly.closesmatplotlib#16463.

The way that bbox_inches='tight' is implemented we need to ensure thatwe do not try to adjust the aspect during the draw (because we havetemporarily de-coupled the reported figure size from the transformswhich results in the being distorted).  Previously we did not have away to fix the aspect ratio in screen space of the Axes (only theaspect ratio in dataspace) however in 3.3 we gained this ability forboth Axes (matplotlib#14917) and Axes3D (matplotlib#8896 /matplotlib#16472).Rather than add an aspect value to `set_aspect` to handle this case,in the tight_bbox code we monkey-patch the `apply_aspect` method witha no-op function and then restore it when we are done.  Previously wewould set the aspect to "auto" and restore it in the same places.closesmatplotlib#16463.

The way that bbox_inches='tight' is implemented we need to ensure thatwe do not try to adjust the aspect during the draw (because we havetemporarily de-coupled the reported figure size from the transformswhich results in the being distorted).  Previously we did not have away to fix the aspect ratio in screen space of the Axes (only theaspect ratio in dataspace) however in 3.3 we gained this ability forboth Axes (matplotlib#14917) and Axes3D (matplotlib#8896 /matplotlib#16472).Rather than add an aspect value to `set_aspect` to handle this case,in the tight_bbox code we monkey-patch the `apply_aspect` method witha no-op function and then restore it when we are done.  Previously wewould set the aspect to "auto" and restore it in the same places.closesmatplotlib#16463.