Split the header into two or three parts, depending on the number of
columns shown. The farm status indicator will be above the middle column
(in 3 col mode) or at the right edge of the left column (in 2 col mode).
Also I reverted the hiding of the farm status when SocketIO has
disconnected, as that disconnect happens when navigation between tabs.
That created a too 'blinky' interface, so now it just shows the last-known
farm status.
