JPL DE 438

I’ve been studying this ephemeris for some time. It is useable from 1550 to 2650 CE only, but contains several improvements with respect to DE430 due to new positional data coming from Messenger, Mars Odissey, MRO and Juno missions. Coefficient files are pretty small so I can embed them into the application itself and let the user choose if he really needs DE431 for analyzing events placed out of the above range. The DE438 code is already under test, and when I’ll be sure that everything is working fine I’ll proceed with merging the new code into the application.