Sphenix pressure floor

doc/RTD/source/HydroSchemes/sphenix_sph.rst

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

examples/SubgridTests/PressureFloor/README

examples/SubgridTests/PressureFloor/getGlass.sh

examples/SubgridTests/PressureFloor/makeIC.py

examples/SubgridTests/PressureFloor/plotDensity.py

examples/SubgridTests/PressureFloor/pressureFloor.yml

examples/SubgridTests/PressureFloor/run.sh

src/hydro/SPHENIX/hydro.h

src/hydro/SPHENIX/hydro_part.h

src/pressure_floor.h

src/pressure_floor/GEAR/pressure_floor.h

src/pressure_floor/none/pressure_floor.h