games/snes: faster scaling

load x-stretched scanline and use image replication bit to let
devdraw do the y-stretching. this reduces slow RGB15 -> display
conversions as devdraw caches small numbers of converted source
scanlines (one in hour case). setting pixels should also be a
bit faster. (only 3 writes instead of 9 for x3 scaling)
libmach: fix printing of amd64 modrm byte register with rex prefix
add /rc/bin/aanuke
aan(8): add HISTORY
aanuke: check both /net and /net.alt (thanks, mischief)
aanuke: only print commands to kill the current user's aan procs
vga: add support nVidia 7600GS (and possibly 7950) (from kenji okamoto)
vgadb: add EIZO Flexscan S2231W (from kenji okamoto)
merge
kernel: fix printing wrong memory sizes in pageinit(), overflowed on amd64 (thanks aram)