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.
please people, remember to keep source UTF-8 and if you're committing on behalf of others, clean up indents to meet MAME conventions
anyone can run srcclean over a submission and see what will get hit
