chain module: setbpb changes, bss & bs options, bugfixes

chain module: setbpb changes, bss & bs options, bugfixes

Generic function detecting BPB type (7 versions) have been added.
set{hid,geo,drv} have been replaced by single setbpb option, using
mentioned function to make more precise decisions what to update where.

Full BSS and BS emulation has been added, also employing BPB detection.

Some logic/flow changes in chain's main(). There was also a bug, in
which backup sector was populated with wrong data.

Appropriate documentation updates.

Signed-off-by: Michal Soltys <soltys@ziu.info>