zfsboot and zfsloader: normalization of filesystem names

[Andriy Gapon]

Currently zfsboot uses the following format to specify a ZFS filesystem name in
a full file path:
poolname:filesystem/name:/path/to/file
ZFS loader uses this format:
zfs:poolname/filesystemname:/path/to/file

The following patchset:
http://people.freebsd.org/~avg/zfs-boot-naming.diff
unifies the naming.
zfsboot format will be: poolname/filesystemname:/path/to/file
Note that it is still different from zfsloader - "zfs:" prefix is missing.  This
is because unlike the loader zfsboot supports only ZFS filesystem, so the prefix
is redundant.  But I can still add support for it if there is a popular request.

Also, current code treats lone pool name as a pool's boot data set name.  That
is, whatever is specified in bootfs property.  If the property is unset, then
the root dataset is the boot dataset.
I want to change this to always mean the root dataset.  boot dataset is selected
by default anyways and its name is expanded to the actual name when it is printed.

Also, lsdev -v for a zfs pool will print bootfs property.
The same goes for zfsboot's "status" command.

A final note.  All this stuff really needs to be documented.  Currently the
documentation on boot blocks seems to totally miss on ZFS boot.

-- 
Andriy Gapon