Switch to only using ticks for repartition weights, avoid the problem of early repartitioning by not doing that, the memory balance initial partition is good enough to start with

When repartitioning, no need to verify that the multipoles were drifted. We are going to free them anyway.

Matthieu Schaller authored Nov 08, 2018 and Matthieu Schaller committed Nov 10, 2018

More uniform way of looping over pairs of top-level cells for the proxy construction, gravity pairs construction and hydro pairs construction.

When resuming from a check-point file, we do not have the list of local top-level cells for the original drift all. Use all the cells instead.

Move the MPI type for multipole to a separate file. Create a bit-by-bit XOR reduction operation for multipoles. Utilise that reduction operation when exchanging the top-level multipoles.