Isentropic interpolation function added.
Isentropic interpolation function added.

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