Sprite: Swap record fields of Sprite constructor.

Doesn't change any functionality but makes it more elegant to write
sprites, for example:

ledBar :: Sprite
ledBar = Sprite mkBarPixels [apic|
    +-----------------------------------------------+
    |ccccccccccccccccccccccccccccccccccccccccccccccc|
    |c111111111111111222222222222222333333333333333c|
    |c111111111111111222222222222222333333333333333c|
    |ccccccccccccccccccccccccccccccccccccccccccccccc|
    +-----------------------------------------------+
|]

Signed-off-by: aszlig <aszlig@redmoonstudios.org>