Compiling with -Wextra and suppressing known unused parameters
Server ERROR messages for terminating connections
Whole lot of changes and fixes:

- restructured how servers and channels are organized
- removed arbitrary limit on number of server
- improved how the channel bar is drawn to match new organization
- channel_switch() handles moving next/prev according to the new
  organization
- improved signal handling:
    - sigwinch is now reentrant and handled synchronously in the main
      loop
- fixed a memory leak in the connect thread cleanup
- fixed a memory leak in strdup
- a whole bunch of other fixes, improvements and cleanups