Feature suggestion: Plugin recipes for SimPlot

This is an idea I just had but don't want to work on for now: A plugin is a tuple of a function f and an Attributes a. When an array of plugins is passed to the simulation plot, it does plot!(simulationplot, f(sim), a...) for every plugin (possibly in an order that can be set by passing a z index so you can plot over and under the existing elements).

Potential applications are

• non-standardized InPartS objects (e.g. fields), write a plot recipe for your field type & use a plugin to add it to the simulation plot. Yes, you could just plot two things, but then you'd have to update both of them simultaneously for animations! that's hard!
• things like dipoles: write a function that collects the dipoles and wraps them in a custom type, add a plot recipe for that type and you're done.

Since this is an idea that would come with moderate effort (the z-index bit requires some thought) and minimal benefit, it's ultra low priority, but I wanted to keep it written down somewhere just in case