JulianDate.getSecondsDifference consistency

[pjcozzi]

Given that Cartesian3.subtract(a, b) is a - b, shouldn't a.getSecondsDifference(b) also be a - b? Currently, it is b - a.

[mramato]

JulianDate needs to be completely refactored to meet our current standards. It was one of the few core classes that never got transitioned over.

[andr3nun3s]

I can pick this up if you want, just tell me what needs to be done.

[mramato]

@Andre-Nunes I think we need a larger pass on JulianDate than just this one change, so I would hold off on this for now (we aren't sure what we want to do yet, we just know it needs a lot of cleanup). If you are looking for stuff to do, there are a bunch of little issues that have been building up; off the top of my head #913 and #1299 might be a few good ones to knock off (and you'll get to learn about an area of the code you haven't worked with yet I believe).

[pjcozzi]

CC #405

[pjcozzi]

Closing as duplicate with #1407.