Final quadrature cleanup

[sglyon]

I have reviewed the quadrature branch and I think that code is ready to merge.

There are a couple of things that we should still clean up soon, but that shouldn't prevent the branch from being merged. Here are the residual clean-up items:

• In the docstring for qnwequi we don't know what the equidist_pp argument does.
• We need to fill in a description of the docstring for ce_util.gridmake
• The example notebook has a lot of code and pretty pictures, but not much exposition. It could use some love to make it a better teaching tool.

[mmcky]

@spencerlyon2 Are these items still outstanding? Can I close this issue. It appears there is a merged PR.

[sglyon]

Yes, I think we still need to clean up that notebook.