* Cleaned up spaces in software list comments.
* megadriv.xml: Improperly indented sharedfeat tag.
* gbcolor.xml: Converted "GBC only" comments into sharedfeat tags.
* a5200.hsi: Fixed a few dispossessed tags.
* Various softlists: Fixed improperly entabulated tags.
* Various softlists: More entabulation fixes.
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.
