Some ease of use suggestions

[dforero0896]

Hi, I've been following the tutorials and have thought of a few things that could be added for ease of use.

• Pass fig or ax objects for the plot functions to use in order to use them to create more complex figures.
• Set data automatically to mean of mocks + rescale covariance. I'm not sure if this exists, I didn;t find it but maybe it is a bit hidden.

Neither of these is crucial since there are workarounds already available but would be nice to have in the future. I'll add to this thread if I think of any more.