READ long - read a long from the given address

 Command:       $AF $06
 Data:          $ww $xx $yy $zz

 read a long from address <$wwxxyyzz>  returns <$qqrrsstt> as result

 Command will be ACK'ed when received.
 Command ACK:   $00 $06
 Command DONE:  $1F $06 $qq $rr $ss $tt