Add "order" dropdown for both spritesheet nodes

[joeyballentine]

closes #2851

[RunDevelopment]

The "row x column" and "column x row" names are confusing. The infix "x" typically denotes multiplication which most people think of as commutative. By this interpretation, these two options describe the same thing (a*b = b*a).

The terms you are looking for are row major and column major. Unfortunately, these terms aren't really used outside CS and math, so we need to explain them. I would probably give a short description of both and then use code blocks to visually show the difference like this:

Row major:
→ 0 1 2
  3 4 5
  6 7 8

Column major:
↓ 0 3 6
  1 4 7
  2 5 8

Also, the description should be a hint (so with a little (i)) IMO. We can't expect people to know this, so we should make the explanation easy to access.