MNT: Code cleanup
MNT: Code cleanup

Use standard cartopy.feature import and move import of shapereader since
it's only used in the one spot. Trying to minimize unconditional import
of Cartopy.

dopplershift/MetPy,ahaberlie/MetPy,ahaberlie/MetPy,dopplershift/MetPy,Unidata/MetPy,Unidata/MetPy,ShawnMurd/MetPy