Previously the upscale test was changing the frame contents with incorrect data
before going back, but the algorithm relies on not changing contents for some
pixels by "skipping" them. Duplicated a bit of code to create a
non-destructive upscale test before decoding the whole frame.
The movies for Crusader: No Remorse have a unique decoder which is not too hard
to implement. Unfortunately, they don't properly implement the "compression"
FourCC, and instead put their ID in the "Stream Handler". Since supporting
them requires a change to the existing Image API, I thought I should make a
pull request for comments.
With this change, the movies in Crusader can all be played nicely.