Print more information about multipoles and cells when an undrifted multipole is encountered in the MM task.

Removed the now obsolete checks that all correct tasks are active. Will need to be re-done correctly.

Just uses abort() instead of exit() in non-MPI code

In kick1 after all is done, update the part's acceleration to include the gpart acceleration. This allows the hydro drift to use the correct accelerations for hydro predictions.

Also activate the gradient self and pair tasks in engine_marktasks() when running with the extra hydro loop

Restore correct dependencies between force loop and kick task when the extra hydro loop is activated.