1. added 3 partition policies on to input stream operator
   shuffle   (roundrobin partition)
   all       (no partition, copy all events to all instances)
   expr      (partition by a hash value of a expr stringfied result)

2. changed the process performance tracing to
   when each instance process event sequence number

3. added time based sliding window
   window(interval [slide interval] )
   following are valid intervals :
   10 second,   10 seconds,  10 minute, 10 minutes,  10 hour, 10 hours, 10 day,  10 days;
   1 day 10 hour 30 minute 5 second;

4. changed count based sliding window syntax
   window(rows 3)           ===>    window(3 rows)
   window(rows 3 slide 2 )  ===>    window(3 rows slide 2 )

5. added 2 more scalar functions
   max(arg1, arg2)
   min(arg1, arg2)

6. added sync policy on to AbstractCommandsExecutor
   window operator will read isSyncByInterval() in seting up executorContext for the operator
   SimpleCommandsExecutor by default uses the policy "sync every event"
   ThreadedCommandsExecutor uses policy "sync per interval",  the default interval is 200K events