[J-core] Simple root filesystem build script on github now.

[Rob Landley]

It's at https://github.com/j-core/mkroot

Geoff's already sent me a bug report (dunno if he's using it wrong or if
I screwed up), and Rich said he wanted to tweak some things, so... There
you go, it's in git now. :)

Yes, I need to get the VHDL source up there too. Working on it...

Rob

(The atmel thing is a flash utility for the turtle board, which nobody
has yet. But just so you know...)