Use the primoridal Helium abundance to compute the Hydrogen mass fraction. Optionally read the temperature transition from the YAML parameter file.

Use the threaded version of FFTW to speed-up the PM part of the code.

See merge request !608

Add option to label snapshots by the time

See merge request !601

Can be uninitialized when task is MPI

Add ParMETIS support

See merge request !506

Conflicts:
	src/partition.c

Prevent users from generating gas from the ICs if they are running without the hydrodynamics policy.

Parallel mesh assignment and simplification of M2L kernel

See merge request !604

Correct debugging check for the size of the collected time-step. A step of size 0 is acceptable on the last step.

Only collect time-steps for hydro and gravity for the cells that have related…

Closes #455

See merge request !605

Use a dedicated MPI type for the pcells. Also use the m-pole MPI type for the communications instead of MPI_BYTE.

Correctly move the reading pointers for the various chunks in the parallel HDF5 i/o module. Increase the hdf5 chunk size to 1MB

Use temporary local copies of the D_xxx terms in the M2L_apply function to help the compiler optimize quantities.