Moved the reductions of sys.epot and sys.ekin to part 1 (output)

Since the potential and kinetic energy is only needed inside the output
part, the reductions of the tmp_epot[i] and tmp_ekin[i] buffers were
moved from the parts in which they were downloaded from the device
(parts 7 and 8, respectively) to part 1 (where the ouput is actually
printed).