Remade the plot in linear terms. Scott seems to prefer this version?

Need to make the yticklabels include 0.55.

I may also add in a flag option to switch between linear and log, because they're both good options.
Merge branch 'master' into linear_hist

Just to get that .gitignore update from upstream.
Now the stetson versus Hmag plot is fully switchable between linear/log.