w: new applet, alias to "who -H"

w: new applet, alias to "who -H"

function                                             old     new   delta
who_main                                             451     463     +12
packed_usage                                       31477   31485      +8
applet_main                                         1508    1512      +4
applet_names                                        2606    2608      +2
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 4/0 up/down: 26/0)               Total: 26 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>