Return packed array

[hpinkos]

This make all pack functions return the packed array. This helpful if I want to do something like

var myObject = {
   position: Cartesian3.pack(position, new Array(3));
} 

I also think it's all around more intuitive. I know we do this a lot, but to me this syntax is weird

Cartesian3.pack(position, array);

And this makes much more sense

array = Cartesian3.pack(position, array);

[pjcozzi]

This is also well-aligned with math functions like Cartesian3.add.

Can you update reference doc, update CHANGES.md, and add full unit tests?

[hpinkos]

@pjcozzi updated CHANGES.md and added doc

I think all classes that have pack use createPackableSpecs to create their pack specs. Since I check for the array to be returned there, I think that should cover all of the functions I changed

[mramato]

Rather than re-assigned packagedArray, create a new variable called returnedArray and do expect(returnedAraray).toBe(packedArray) in order to verify that's what is actually returned.

[mramato]

Except for that one comment, this is fine with me. Thanks, @hpinkos!

[hpinkos]

Thanks @mramato! Updated