JPL Ephemeris manager

manages the JPL planetary ephemeris files both on and off-line

This is a class that manages the JPL planetary ephemeris files from DE102 through DE431t. It can download the ascii files and use them directly or convert them to local binary files. Subsequently, the class can use these files to calculate position, velocity, and acceleration in whichever coordinates is stored. It can also return Nutation, Libration, Lunar Euler angle rates, and TT-TDB values if files contain them.
The class has been fully tested against all DE files available from JPL using JPL provided test points.
Works with DE-102,200,202,403,405,406,410,413,414,418,421,422,423,424,430,430t,431