~/.xmonad: Add screenshot shortcut.

.xmonad/xmonad.hs

        ((mod4Mask .|. shiftMask, xK_Tab), spawn "xkbswap"),
        ((mod4Mask .|. shiftMask, xK_l), spawn "slock"),
        ((0, xK_Print), spawn "scrot -e 'mv $f ~/m/pictures/ 2>/dev/null'"),
        ((mod4Mask, xK_f), sendMessage ToggleStruts),
        ((mod4Mask, xK_q), restart "xmonad" True)
     ]