All gpart now find all of their interactions following correct boundary condition check in runner_do_grav_long_range()

Can now run through all the tasks but still missing some interactions coming from the close-by pairs over MPI

All-reduce all the top-level multipoles after a rebuild() to make sure we have all information in hands to construct the tasks.

Fixed the gravity bugs reported in #363. Need to find a good rebuild criterion for gravity-only runs.

Fix to #363. Drifting decision needs to use the same multipole information as the actual tree walk. Also fix some gravity_cache padding values.

There is a problem when the cpu mask is empty and using multiple MPI ranks on a node, in that case all the main threads end up pinned to one core during the reading of the initial condition (and any other tasks done before engine_init is called).

Force compiler to report shadowed variables. Removed all shadowed variables. Added the function scheduler_activate_send() to simplify the unskipping of MPI sends.

Reinstate missing pointer indirection for external gravity dependencies that had disappeared in merge.

Hopefully still quite conservative

Correct use of caches in the self-PP gravity task. Make sure we can run without vectorization. Make sure we can run without hydro.

Correct use of caches in the self-PP gravity task. Make sure we can run without vectorization. Make sure we can run without hydro.