Merge branch 'test' into 'master'

Readme.md

examples/cooling_rate/cooling.yml

examples/cooling_rate/generate_grackle_data.py

examples/cooling_rate/plot_cooling.py

examples/cooling_rate/run.sh

pyswiftsim/structure.py

setup.py

src/config_wrapper.h

src/cooling_wrapper.c

src/cooling_wrapper.h

src/wrapper.c

test/test_cooling.py