Fix bug in get_delta_tdb_tt using meters where km expected
Update CHANGES.rst
Update documentation example
Merge pull request #1929 from taldcroft/time-tdb-tt

Bug in TDB to TT calculation
Introduce a simple EarthLocation class, subclassed from CartesianPoints
Includes erfa gc2gd so that one can transform XYZ to geodetic
Use location exclusively, deprecating lon and lat (and removing height)
Move conversion of u, v, to "km" to inside the call to erfa