sanlock: io timeout related changes
    
    - the default io timeout is now 10 seconds, which
      impacts the other default timeouts as well
    
    - add an io timeout arg to the libsanlock_direct functions;
      this is especially important for the live_id() function
      which is based on knowing the timeout for a host to be
      dead or alive.  For this to return the correct result, the
      sanlock daemon and live_id() must be using the same io
      timeout
    
    - the -o option sets the io timeout seconds, no others;
      derive all other timeouts from that
    
    - remove the final read in the delta lease renewal function
      since the first read in the next renewal should effectively
      do the same thing.
    
    - allow a long timeout for the renewal write since there's
      no point in letting it timeout, and timing out is probably
      counter productive
    
    - verify our host_id generation also matches when we reread in
      renew to verify we still hold the host_id
    
    - add long comment about timeouts and max/min duration of
      various functions