adding len attribute to Polygon.
adding len attribute to Polygon.

pombreda/pysal,Alwnikrotikz/pysal,tectronics/pysal,tectronics/pysal,Alwnikrotikz/pysal,pombreda/pysal,AlanZatarain/pysal,pombreda/pysal,google-code-export/pysal,AlanZatarain/pysal,Alwnikrotikz/pysal,tectronics/pysal,google-code-export/pysal,AlanZatarain/pysal,google-code-export/pysal,pombreda/pysal,google-code-export/pysal