massive reorganization of the device ops committed.

[Matthew Dillon]

    I've committed a massive reorganization of the device ops along 
    similar lines to the reorganization that I did to the vnode ops.

    Just as was done to the vnode ops, the thread pointer argument has also
    now been removed from all device ops.

    The new device ops are now syslink-compatible, getting us a little further
    along to our clustering and userland VFS goals.

						-Matt