Replaced use of _time_steps for integration with
scipy.integrate.trapz and scipy.integrate.cumtrapz.
in calc_rad_loss().
Replaced use of _time_steps for integration with
scipy.integrate.trapz and scipy.integrate.cumtrapz.
in goes_lx().
Deleted _time_steps() from goes.py and test__time_steps() from
test_goes.py as they are no longer used.