Changed the used pressure from the maximum of the particle pressure, floor and star formation pressure

Put the FPE check back in for now. There might still be unexpected problematic side cases that need special treatment in the enrichment routine.

Small enrichment fixes

See merge request !940

Protect the feedback from 0 ngb stellar evolution and allow a lower thermal energy after enrichment because it can physical happen

Mpi memory clean

Closes #619

See merge request !936

Clarify box_wrap

See merge request !939

Parco 2019 debug

See merge request !930

Pass the hydro_properties to the prepare_gradient function. Make sure rho_dh is sensible when particles get ejected out of neighbourhoods.

Reported by @jborrow, closes #618.

Updated the IsolatedGalaxy_starformation python scripts to use the new snapshot names

See merge request !932

Alternative definition of the number of neighbours

See merge request !926

Add interactive task plot script.

See merge request !921

Re-introduced rho_dh in the Pressure-Energy SPH hydro case to allow for the alternative neighbour number definition.

Conflicts:
	src/fof.c

Conflicts:
	src/engine.c
	src/fof.c
	src/gravity/Default/gravity_part.h
	src/proxy.c