pep8 fixes for mapping.py
pep8 fixes for mapping.py

pedrovma/pysal,lixun910/pysal,lixun910/pysal,lanselin/pysal,weikang9009/pysal,sjsrey/pysal,lixun910/pysal,ljwolf/pysal,ljwolf/pysal,pysal/pysal,ljwolf/pysal