Changeset : add get_sd_over_modes - from waterwingz in ...

add get_sd_over_modes - from waterwingz in ​http://chdk.setepontos.com/index.php?topic=650.msg112323#msg112323
Returns a bit map where the bits are :

can set focus in Autofocus mode (0x01)
can set focus in AFL mode (0x02)
can set focus in MF mode (0x04)