libfdisk: cleanup internal drivers' API

Signed-off-by: Karel Zak <kzak@redhat.com>
libfdisk: add fdisk_set_partition()

Signed-off-by: Karel Zak <kzak@redhat.com>
libfdisk: (dos) implement fdisk_set_partition() backend

Signed-off-by: Karel Zak <kzak@redhat.com>
libfdisk: (gpt) implement fdisk_set_partition() backend

Signed-off-by: Karel Zak <kzak@redhat.com>
libfdisk: (gpt) use generic API to change UUID and name

Signed-off-by: Karel Zak <kzak@redhat.com>
sfdisk: make dump format usable on stdin

Signed-off-by: Karel Zak <kzak@redhat.com>
sfdisk: add missing stuff to usage()

Signed-off-by: Karel Zak <kzak@redhat.com>
sfdisk: add --list-types

Signed-off-by: Karel Zak <kzak@redhat.com>
sfdisk: add --verify

Signed-off-by: Karel Zak <kzak@redhat.com>