luckily, that file turned up as well!
The zip seemed to be corrupt, so I recreated it: After fixing
it with zip -FF I unpacked the result which still showed some errors
and then created a new zip from the unpacked files.
Only guied_ansi.jpg and guied_symbol.jpg of
Adding_Fonts_to_use_in_Quake_4_GUIs are still missing
(and Doom3/skins_imp.png), but so far no one seems to have them
ArtReference_CreatingTextures
ArtReference_Q4Shaders_AnimatedStrips
Basic_FX_file_structure
luckily someone who has backups of most of the missing files turned up!
the last images I could find at archive.org, the other ones listed in
README.md are *really* missing.
also, turned out that some articles were (incomplete) duplicates
of others, removed them
it's more or less usable now!
all images (except for the ones of moinmoin itself) are still missing.
possibly articles are missing as well, haven't checked yet
(and the lost downloads are missing, of course)
