DisplayTranslucentSprite should use TransparentSpriteColor

[IceSoft]

The default transparent color 0 is not always useful.

Better:
DisplayTranslucentSprite() should also use TransparentSpriteColor()

@Fred
If you can add this in PB4 this will be great for PBpuzzle.
I want to use it for the shadows. But I cannot use always color 0 because color 0 can be part of a picture.