update to automated cooling box test, general tidy

examples/CoolingBox/analytical_test.py

examples/CoolingBox/makeIC.py

examples/CoolingBox/run.sh

examples/CoolingBox/test_script.sh

examples/CoolingRates/plots.py

examples/CoolingRates/plots_nh.py

examples/CoolingRates/testCooling.c

examples/CoolingRates/testCooling.yml

src/chemistry/EAGLE/chemistry.h

src/cooling/EAGLE/cooling.c

src/cooling/EAGLE/cooling.h

src/cooling/EAGLE/cooling_struct.h

src/cooling/EAGLE/eagle_cool_tables.c

src/cooling/EAGLE/interpolate.c

src/cooling/EAGLE/interpolate.h

src/engine.h