updated scarlet tutorial

[ismael-mendoza]

This PR will revive the Scarlet tutorial so that it runs with the latest version of scarlet installed in the Stack. Resolves #166

The last part of the tutorial Update Functions seems deprecated in a way that I can't quite figure out how to fix. It seems that this has to do with using different constrains, although it's possibly done in a very different way now. Maybe remove this part?

[kadrlica]

@fred3m would you be willing to take a look at this?

[fred3m]

Sure.

@ismael2395 could you please remove the images, rebase, and force push the changes? It's hard to see what's changed with all of the images in the notebook, plus it will take up too much space if we always save images in the repo.

But I looked at the notebook version and on first glance it looks good but I have a few additional change requests:

• I would change e_rel to 1e-4 or 1e-5 to allow scarlet to run for a few more iterations. There's a lot of flux leftover in the residuals that it should be able to model with another 20-30 iterations. Or possibly leave it as it and invite the user to modify e_rel to higher and lower values to better understand how it affects the results.

• The update cell is no longer useful because we no longer do constraints that way. So for now I'd recommend just deleting those cells and if you want to open up a ticket and assign it to me I'll create a new cell or two that illustrates how to apply constraints in the newest version of scarlet.

Thanks for keeping the notebook up to date!

[ismael-mendoza]

Thanks @fred3m for your suggestions. I incorporated them and I now I'm just trying to rebase and merge - I might close this PR instead and start a new one to avoid having to force push