Refactor generation script.
Refactor generation script.

This makes it easier to handle multiple files.

ahaberlie/MetPy,deeplycloudy/MetPy,ShawnMurd/MetPy,Unidata/MetPy,Unidata/MetPy,ahaberlie/MetPy,dopplershift/MetPy,dopplershift/MetPy,ahill818/MetPy,jrleeman/MetPy,jrleeman/MetPy