the basic idea is to change clean up procedure to 2 steps,
the 1st step only marks the time controller as to be cleaned up,
the 2nd step executes in the timer thread and does the
actual job to avoid race.

I also change `pCtrl->ticks = rand() / pCtrl->maxTicks` to
`pCtrl->ticks = rand() % pCtrl->maxTicks`, because I think
this is a typo but not sure about this.

enhance robustness of scheduler

fix dead code

upload code for cassandra/tdengine test

1. check all memory allocation failure in `taosInitScheduler`;
2. make `pSched->numOfThreads` the actual number of created threads
to avoid crash in `taosCleanUpScheduler` when `pSched->qthread` is NULL
and other issues;
3. check interruption of `sem_wait` in `taosScheduleTask`,
and use `pTrace` instead of `pError` when `sem_wait` was interrupted;
4. cancel all threads before join them to enable cocurrent cancellation;
5. remove unused global variable.

alter displaying information for default value of some options in taosdemo

change direcotry from taosbenchmark to taosdemo in CMakeList.txt

Return records with seperated fields in Lua connector.

fix memory leak in os/linux/src/os.c::taosInitTimer #304 

Modify  json's date to Json standard time format ISO-8601

Field names and values are both returned. Client application gets value by field name. It runs as convention except that bool type is returned as one byte,tiny integer. Bool type will be returned in future if tiny integer causes confusion.

change the range of int data to 0-49

Signed-off-by: NH-ZeX <hzx20112012@gmail.com>

Signed-off-by: NH-ZeX <hzx20112012@gmail.com>