Note also needs --enable-compiler-warnings=yes and --disable-vec and isn't known to run!

The lenghts are checked against the expected values and cause an error, the labels are not currently used (would need to add API to return the headers so that these could be speculatively queried and the stream rolled back, so maybe not a great idea).

Needed to save and restore the current partition

Moved restart_write into engine_step and trigger after drift_all

Unify the first initialisation of the part and xpart arrays. Correctly set the ti_drift and ti_kick for gparts and sparts.

Better function name for the first initialiation of all the parts at the very start of engine_init_particles()

Add the possibility to read basic chemistry information from the parameter file and propagate this onto the particle at initialisation time. More uniform naming convention for the first initialisation of properties.

Better naming convention for the cell_split variables in the YAML file. New variable for the splitting of gravity pairs.

This reverts commit 10f04895.

Re-introduce the 'end_force' function as a task in order for the cooling function to be called at the right place in the time-step.

Correctly compute the separate time-bins for hydro and gravity at the bottom of the tree in space_split_recursive()

Separate the time-step information for hydro and gravity tasks into two different set of variables for each cell.

Fixed a moronic bug. Unskipping MPI sends and recvs for gravity should not be done *only* for local pairs. Obviously....