Plonk example: dust-gas protoplanetary disc with embedded planet

Sample Phantom (https://github.com/danieljprice/phantom) smoothed particle hydrodynamics data for demonstrating Plonk (https://github.com/dmentipl/plonk). The dataset is a simulation of a dust and gas protoplanetary disc with an embedded planet. The dataset contains 30 snapshot files, several time series files, and several parameter files. See the examples section of https://plonk.readthedocs.io/ for more.