also, fix typo in __main__.py

I messed up the nprocesses/nthreads parameter

also, remove hardcoded lack of activity/rotation.

also add preliminary script to generate dependency list.
we should use this for compiling in the future.

NSVEparticles test works.

by default a new field object (pressure) is generated every time the
acceleraation is computed in vorticity_equation. I now allow for an
externally allocated pressure field to be used, thus avoiding the
creation of a new field object every niter_part.