improve parenting for large areas with rank 30

improve parenting for large areas with rank 30

Instead of unconditionally parenting them to a street, the
larger areas get a parent area that contains them. To keep
things computationally light-weight, only use the centroid and
bbox to determine if an area is contained.

Requires renaming of parenting functions because renaming
a parameter of the function causes issues when updating the
function (it requires a manual delete, which I'd like to
avoid).