Implements unrotated planar YUV 4:2:0 -> RGB24 conversions in Y2R.
Currently only the Y (luma) channel is used, so the results don't
contain color. This will be added in a later PR at some point.
This is enough to get all currently know Moflex videos to decode. (Some
don't display on-screen due to seemingly unrelated reasons.)
Thanks to @archshift for doing the initial implementation which I
cleaned up and then fixed the 8x8 block mode.
Involves making asserts use printf instead of the log functions (log functions are asynchronous and, as such, the log won't be printed in time)
As such, the log type argument was removed (printf obviously can't use it, and it's made obsolete by the file and line printing)
Also removed some GEKKO cruft.
There is no documentation available on this function, but we set the result to false as a stub.
This allows Super Little Acorns to move all the way in game with pp3c.