CO2 calculator results in deprecation warning

[alexanderweiss]

co2_calc.py:35: VisibleDeprecationWarning: Reading unicode strings without specifying the encoding argument is deprecated. Set the encoding, use None for the system default.
  flights = np.genfromtxt(input_file, delimiter=';', names=True, dtype=None)

Looking at the issue it seems like encoding='latin1' for np.genfromtxt