Feature request: nice grouping in postscript output

Hi John et al.,

I just had a chance to play with matplotlib for a few minutes, and I'm very encouraged!

A feature request: I frequently use Adobe Illustrator to touch up postscript files that contain my figures. In this case, it is REALLY handy when the postscript files group nicely. Knowing little-to-nothing about PostScript and Illustrator, I have no idea how hard the behavior is to implement, but it would be fantastic if it did.

I just tried a few things with the axes_demo and the errorbar_demo in the examples directory. I liked that the points grouped together. I didn't like that in the errorbar_demo that the points and the errorbars grouped together almost inseparably.

With the demos tested, the primary curve or points grouped with a rectangle around the plotting region that had no fill or stroke but seemed to clip the contents to within that box. I wonder if it would be nicer to produce postscript output where the clipping is done before rendering to a file, thus eliminating the need for this rather strangely behaved box?

Also, the generated plots have some two boxes, one with a white stroke and one with a white fill, surrounding the figure. These, too, seem unnecessary.