If <tt>plot_map_pbc = 1</tt>, atoms will be mapped to the primary domain, i.e. with scaled
coordinates in the domain [-0.5, 0.5), when plotting in the X-window.  Note that this is only
for visualization purposes.  The actual (scaled or real) coordinates are not changed.

<p>
By default, the actual coordinates of the atoms are used in the plotting, so atoms can appear 
outside the primary domain (i.e. the purple-colored simulation box).
