Looks like the URL for this specification of the PCX format is becoming
unstable on this site, lately -- let's just use a stable URL at
web.archive.org instead.
Also, when referencing the FFmpeg PCX decoder, link to an FFmpeg
release tag that should be close to what was checked back when this
was committed.
The modern web is mostly HTTPS now, and some browsers may start giving
warnings when one uses a plain HTTP connection.
Only update the protocol when the HTTPS connection exists and fully
works. Code from external projects/tools is kept as is.
The RGB planes were flipped and TESTBED image decoder tests revealed this bug. AGS is the only engine that allows for 24bpp PCX image, but an example game is currently unknown.