Add spacecraft location coordinates to returned data

[jgieseler]

The original CDF files (at least HET level 2) contain spacecraft location coordinates (R, heliocentric latitude & longitude), these should be contained in the returned data.

print(t_cdf_file.varattsget('HCI_R'))

{'FIELDNAM': 'S/C Radial Distance', 'CATDESC': 'Spacecraft radial distance from the Sun', 'FILLVAL': array([-1.e+31], dtype=float32), 
'LABLAXIS': 'r', 'UNITS': 'au', 'VALIDMIN': array([0.], dtype=float32), 'VALIDMAX': array([1.2], dtype=float32), 'SCALEMIN': array([0.], 
dtype=float32), 'SCALEMAX': array([1.2], dtype=float32), 'VAR_TYPE': 'support_data', 'SCALETYP': 'linear', 'VAR_NOTES': ' ', 
'DEPEND_0': 'EPOCH_6', 'FORMAT': 'F6.4', 'SI_CONVERSION': '1.495978E11>m'}