Merge branch 'GrackleCoolingUpdates' into 'master'

doc/RTD/source/SubgridModels/GEAR/index.rst

examples/Cooling/CoolingHeatingBox/README

examples/Cooling/CoolingHeatingBox/coolingBox.yml

examples/Cooling/CoolingHeatingBox/getGlass.sh

examples/Cooling/CoolingHeatingBox/getResults.sh

examples/Cooling/CoolingHeatingBox/makeIC.py

examples/Cooling/CoolingHeatingBox/plotResults.py

examples/Cooling/CoolingHeatingBox/run.sh

examples/parameter_example.yml

src/cooling/EAGLE/cooling.c

src/cooling/EAGLE/cooling.h

src/cooling/PS2020/cooling.c

src/cooling/PS2020/cooling.h

src/cooling/QLA/cooling.c

src/cooling/QLA/cooling.h

src/cooling/QLA_EAGLE/cooling.c

src/cooling/QLA_EAGLE/cooling.h

src/cooling/const_du/cooling.h

src/cooling/const_lambda/cooling.h

src/cooling/grackle/cooling.c