boxspring_figure.py is missing

[dmikushin]

The module referred from boxspring_figure_anim.py is missing:

# make sure that we find the boxspring_figure module in ../oo:
#sys.path.insert(0, '../oo')
# better:
sys.path.insert(0, os.path.join(os.pardir, 'oo'))
from boxspring_figure import draw, set_figure_size