Draft: little-big-adventure: Add support for latest GOG release

I cannot get this to package despite having all elements, because the md5sums of flac files cannot be relied on. For example, their metadata block contains the encoder name and version strings.

I could manually confirm the flacsums match, but:

• there seem to be no support for flacsums in g-d-p except in make-template
• the md5 check happens anyway, preventing a match

I think it is going to need a significant extension to g-d-p to support such game. I can imagine the following approaches:

• add support for flacsum, which would ignore (conflict with ?) other checksums and size for such file when looking for matches.

  This would benefit from a way to express size-and-md5-less group of files, which I believe is not currently possible.

• implement a transcoding step after matching the original wav files, which may be reproducible from the same source data. Then, g-d-p can stick to the existing hash checks, and would then transcode the wav files to flac/ogg during packaging.

  Once step further, g-d-p would extract those .wav files from the still-included (but named slightly differently, with with same hashes) disc image .bin file (LBA.DOT instead of LBA.GOG). LBA.DAT of course gets a new checksum as it references a different name...

Maybe it should be moved to data/wip ?