  * Implemented time-precision for select statements. We can later extend the
    query language with support for querying with another time-precision.
  
  * When queue-full status is set, leave it set even when a new status update 
    is received.
    
  * Mark a server as unavailable when a time-out on a flags package is
    received. The unavailable status prevents sending select queries and
    insert new data to this server. This status flag will never be applied to
    the 'last' server in a pool and will be removed when a new status update 
    from the flagged server is received.
  
  * Cleanup optimize task in case a memory allocation error has occurred.
  
  * Fixed QPack length check for strings. Corrupt or invalid qpack data can
    contain a string length which is not actually available within the data.
    This fix corrects the check for such invalid string length.
    
  * Replaced int with int64_t where required in expr.c.