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.
* hp9825: optional ROM cartridges added (9825b only, ATM)
* hp9825: optional ROMs added to 9825t, added support for banked ROMs
@5c00, separated RAM & ROM spaces in 9825t
* hp9885: added missing post-amble when writing sectors on disk
* hp9825: added acknowledgments to comments (nw)
* hp9825: changes requested by V.Crabb (nw)
