Write MAD Competition and Metamer tutorials about plenoptic

[billbrod]

We have some tutorials now for all of these, but all will need some more work.

Specific feedback:

Metamer

break up with more headers/subheaders
Should include portilla-simoncelli

MAD Competition

from Lyndon: "I found it hard to understand what exactly the plots mean when I'm looking at them. Could perhaps in more detail say what's going on in each of the subplots after the 5th cell, containing:

mad.synthesize('model_1_min', store_progress=True, max_iter=200)
fig = mad.plot_synthesis_status()

Some thoughts I think readers may have:

Are the two right subplots representation error? Or is the lineplot loss the representation error.
Why do you say the loss decreases but then both of them change direction and converge to the same value?
You outline the four cases in the intro, but can you give me some intuition on what I should expect to see in the loss plots before you show the first one to me?
Some subheaders to break up the sections would be nice."

Simple MAD

Would be nice to have a notebook like Simple MAD for all synthesis methods: really simple model and image, so we can plot what's happening in image/representation space.

Synthesis

Currently, this is a notebook, but unless there's something executable to put in it, should move it to documentation.

[billbrod]

Closing this because the first pass of these has been completed, though they can still use improvements