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.
-----------------------------------------------
pv2000: Exciting Jockey [SSJ, Team Europe, Dustin Hubbard]
pv2000: Real Number Basic [SSJ, Team Europe, Dustin Hubbard]
pv2000.xml: desoldered and redumped ROMs for rakugaki and excitem2 [SSJ, Team Europe, Dustin Hubbard]