Updated docstring of calc_rad_loss()
Updated docstring of calc_rad_loss()

Replaces usage of exceptions module

Introduced usage of np.asarray() and np.asanyarray() instead of using
np.array() to convert a variable to a numpy array.

Alex-Ian-Hamilton/sunpy,Alex-Ian-Hamilton/sunpy,dpshelio/sunpy,Alex-Ian-Hamilton/sunpy,dpshelio/sunpy,dpshelio/sunpy