Added checkout support to porcelain.clone. It's enabled by default
to mimick default git clone behaviour

Signed-off-by: Jelmer Vernooij <jelmer@samba.org>
Update NEWS, add tests for clone with bare.
Support filesystems with 64bit inode and device numbers.

stat(2) can return 64bit filesystem inode and device, truncate them to 32bit.

Signed-off-by: Jelmer Vernooij <jelmer@samba.org>