Improve cooling rates plot
The plotting script in
examples/CoolingRates/ plots the cooling rates per element as a function of temperature for a given n_H, z and Z array. It would be great to add z, n_H and the metallicity values on the generated figures.
It would also be good to add a header including units and the name of the element to the cooling_element_XX.dat that are generated.
That test should also run when compiling with a different SPH scheme. I changed it to only compile with Gadget-SPH but that test should really be agnostic of the method used.