I was experimenting with an alternative way to calculate Pluto's position.
That idea didn't work out, but in the process, I did make some changes
I want to keep:
1. A typecast in generate/codegen.c that eliminates a build warning
in Windows (Visual Studio 2015).
2. Expanded generate/vsop/vsop.c to calculate both position and velocity
vectors. This was tricky to get working, and could come in handy.
Can now calculate the heliocentric Solar System Barycenter (SSB)
and Earth/Moon Barycenter (EMB).
Changes made in C, C#, JavaScript and Python:
Added new body codes SSB, EMB.
Added support for calculating both in HelioVector functions.
Verified that all calculations match NOVAS.
Verified that all calculations match each other across languages.
Include an extra 4 terms in the radial component of the VSOP
model for Neptune. The code automatically picks the 4 terms
that maximize the time derivative's highest possible contribution.
The VsopTruncate function had logic to remove any trailing
empty series from a coordinate formula. Now I have split
this out into a separate function called VsopTrim.
I did this because I want to experiment with re-extending
VSOP models to improve prediction of planet apsides,
so some series that are empty might become non-empty again
before being saved to disk.
