[PATCH RFC v3] ubi-utils: Introduce a utility ubidump

[hujianyang]

Hi all,

It's about two months after the pushing of my v2 patches. I'd like
to resend these v3 patches and discuss with you about the debugging
of UBIFS. I wish you are not tried with this stuff.

I have to say these v3 patches don't make a great difference with
the previous versions. Just simplify, I've removed ubi-level dump.
So the lpt-leb dump is not supported as before. I want to know if
we could start at this version and add other functionality step by
step.

Thanks~!

v1:
http://lists.infradead.org/pipermail/linux-mtd/2014-July/054541.html

v2:
http://lists.infradead.org/pipermail/linux-mtd/2014-July/054831.html

Changes in v3:
 - Remove ubi-level dump so we don't need to worry about how to
   get ubi-level info from an UBI device.
 - Read ubifs stuff by read() ops which is provided by UBI driver.