Get rid of a couple of copies of the CC0 text. Add header comment to
CC0 files to remind people editing them what the terms are. Also add
some missing XML headers. The header comments in layouts won't bloat
the binary - they get stripped out before compressing, same as any other
comments.
slot device, moved FDD expansion to be a slot card, added
emulation of the VDP expansion as another slot card. This
makes Gun Fright, TwinBee and Zanac playable if you launch
them with "-ext1 vdp" option. If you want to emulate a
SPC-1000 with floppy drive, you have to add "-ext1 fdd"
instead. [Fabio Priuli]
out of whatsnew: disk emulation still does not work (unless we use
Meeso Kim's patched BIOS), but emulation is now closer to the real
functionality and we needed the changes for the VDP unit emulation.
