[Yaffs] YAFFS2: First checkin

[Charles Manning]

Hi YAFFSers

I have just checked in some YAFFS2 stuff. This will currently do YAFFS Di=
rect=20
and work with emulated 2kpage devices as well as supporting the older 512=
byte=20
pages in YAFFS1 format via a tags compatability layer.

YAFFS2 supports YAFFS1 format for two reasons:
* Don't want to keep two code bases alive.
* During the development oif YAFFS2 I was able to speed up some things fo=
r=20
YAFFS1 too. These have not been back-ported to the YAFFS1 code.

Next step is to finish off the Linux kernel support and utils....

-- Charles