Merge branch 'xy-varagn' into 'master'

examples/EAGLE_ICs/EAGLE_100/eagle_100.yml

examples/EAGLE_ICs/EAGLE_12/eagle_12.yml

examples/EAGLE_ICs/EAGLE_25/eagle_25.yml

examples/EAGLE_ICs/EAGLE_50/eagle_50.yml

examples/EAGLE_ICs/EAGLE_50_low_res/eagle_50.yml

examples/EAGLE_ICs/EAGLE_6/eagle_6.yml

examples/EAGLE_ICs/README

examples/EAGLE_low_z/EAGLE_12/eagle_12.yml

examples/EAGLE_low_z/EAGLE_25/eagle_25.yml

examples/EAGLE_low_z/EAGLE_50/eagle_50.yml

examples/EAGLE_low_z/EAGLE_6/eagle_6.yml

examples/SubgridTests/BlackHoleSwallowing/swallowing.yml

src/black_holes/EAGLE/black_holes.h

src/black_holes/EAGLE/black_holes_io.h

src/black_holes/EAGLE/black_holes_part.h

src/black_holes/EAGLE/black_holes_properties.h