Merge branch 'master' into shadowswift_new

INSTALL.swift

examples/BigCosmoVolume/makeIC.py

examples/CoolingHalo/makeIC.py

examples/CoolingHaloWithSpin/makeIC.py

examples/DiscPatch/GravityOnly/makeIC.py

examples/DiscPatch/HydroStatic/makeIC.py

examples/HydrostaticHalo/density_profile.py

examples/HydrostaticHalo/internal_energy_profile.py

examples/HydrostaticHalo/makeIC.py

examples/HydrostaticHalo/velocity_profile.py

examples/IsothermalPotential/makeIC.py

examples/Noh_3D/makeIC.py

examples/SineWavePotential_3D/plotSolution.py

examples/main.c

src/active.h

src/engine.c

src/engine.h

src/runner.c

src/space.c

src/task.c