libfdisk: support nested MBR

Signed-off-by: Karel Zak <kzak@redhat.com>
fdisk: add 'M' to access GPT nested protective/hybrid MBR

Signed-off-by: Karel Zak <kzak@redhat.com>
libfdisk: fix printf stuff

Signed-off-by: Karel Zak <kzak@redhat.com>
fdisk: fix printf stuff

Signed-off-by: Karel Zak <kzak@redhat.com>
libfdisk: (dos) be more verbose when change bootable flag

Signed-off-by: Karel Zak <kzak@redhat.com>
libfdisk: support extended attributes modification

 * GPT attributes defined by standard (e.g. legacy boot etc.)
 * attributes (bits 48-63) reserved for GUID specific attributes (used for example
   by MS Windows)

Signed-off-by: Karel Zak <kzak@redhat.com>
fdisk: (gpt) add A,B,R,S expert commands to modify attributes

Signed-off-by: Karel Zak <kzak@redhat.com>
fdisk: reorder intro warnings

Signed-off-by: Karel Zak <kzak@redhat.com>
libfdisk: warn about obsolete signatures on the device

Signed-off-by: Karel Zak <kzak@redhat.com>
docs: update TODO, wipe check for fdisk already implemented

Note that rather than implement wipe command in fdisk it's better
inform users to call wipefs(8).

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