Runs a uniform box exposed to constant heating and ionization rates.
This tests is the Iliev+2006 (ui.adsabs.harvard.edu/abs/2006MNRAS.369.1625I/) 
Test 0 part 3, however without stopping the heating and ionization rates
after 0.5 Myr. While the cooling is present, gas heats up and ionize.

To run with GEAR-RT, configure swift with:
  ./configure --with-cooling=grackle_1 --with-grackle=$GRACKLE_ROOT