Added Quick Lyman-alpha cooling and chemistry model

configure.ac

src/Makefile.am

src/chemistry.h

src/chemistry/QLA/chemistry.h

src/chemistry/QLA/chemistry_iact.h

src/chemistry/QLA/chemistry_io.h

src/chemistry/QLA/chemistry_struct.h

src/chemistry_io.h

src/chemistry_struct.h

src/cooling.h

src/cooling/QLA/cooling.c

src/cooling/QLA/cooling.h

src/cooling/QLA/cooling_io.h

src/cooling/QLA/cooling_rates.h

src/cooling/QLA/cooling_struct.h

src/cooling/QLA/cooling_tables.c

src/cooling/QLA/cooling_tables.h

src/cooling/QLA/interpolate.h

src/cooling_io.h

src/cooling_struct.h