Using key is clearer than cmp for sorting
Fix to to put largest intersections first in the list
A list comprehension is clearer than using filter()
Take advantage of [] being falsy
Fix the calculation of overlap between polling unit and larger areas

Previously this was taking the smallest polygon out of any of those
that make up either area and using that as the denominator of the
calculation.  This doesn't seem right; what we want is to see how
much of the LGA area that contains the polling unit intersects with
the larger area.
Add some missing MapIt areas to add to Pombola Place objects

This includes a CSV file with some data that needs to be updated
and the one-off script to apply the changes.