__repr__ for VectorSum objects not correct

[JoshPaterson]

Sorry for so many issues at once, this is the last one for a while.

When I create a vector from the earth to the moon like this:

earth = ephem['earth']
moon = ephem['moon']

earth_to_moon = moon - earth

print(repr(earth_to_moon))

I get this result:

<VectorSum of 4 vectors 301 MOON -> 399 EARTH>

I believe this is backwards, it actually represents a vector from 399 EARTH -> 301 MOON.

Even stranger behavior happens if I do this:

print(repr(moon - earth + earth))

I get this:

<VectorSum of 6 vectors 0 SOLAR SYSTEM BARYCENTER -> 399 EARTH>

Based on looking at the positives and negatives the two earth's do in fact cancel out and the vector is correct, just the __repr__ is incorrect and should be 0 SOLAR SYSTEM BARYCENTER -> 301 MOON:

[brandon-rhodes]

Sorry for so many issues at once, this is the last one for a while.

Don't apologize! 😃 It's very valuable for me to be able to correct these before the next release.