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.
The following constructs are now working:
mess pegasus forth11
mess pegasus forth13
mess pegasus pascal
mess pegasus xbasic
if you use writeconfig=1, you may need to manually unload the roms before loading a new set.
