Code formatting

src/chemistry.c

src/chemistry/EAGLE/chemistry.h

src/chemistry/gear/chemistry.h

src/chemistry/gear/chemistry_io.h

src/chemistry/none/chemistry.h

src/cooling/EAGLE/cooling.h

src/cooling/EAGLE/cooling_io.h

src/cooling/const_du/cooling.h

src/cooling/const_du/cooling_io.h

src/cooling/const_lambda/cooling.h

src/cooling/const_lambda/cooling_io.h

src/cooling/grackle/cooling.h

src/cooling/grackle/cooling_io.h

src/cooling/none/cooling.h

src/cooling/none/cooling_io.h

src/debug.c

src/engine.c

src/engine.h

src/parallel_io.c

src/serial_io.c