Alternate way to get bounding box using pwu::Extents

This version uses "pwu::Extents enclose" and "pw::Entity getExtents" to compute a bounding box without having to explicitly loop over all the points. Note that this version works for database entities as well.
Merge pull request #1 from pabakertx/patch-1

Alternate way to get bounding box using pwu::Extents