* change base_dir to system_dir

* show timeseries by fetchSize
* add ShowTimeseriesDataSet
Co-authored-by: NSailVR <16231015@bjtu.edu.cn>
Co-authored-by: NSail <37333508+SailVR@users.noreply.github.com>
Co-authored-by: NHaonan <hhaonan@outlook.com>

* a premerge for the distributed version
* add sync thread interruption
* fix dead wait in SyncServerManager and add retry

* refactor the thrift rpc service to reduce duplicate codes of RPC and Sync module
* fix bug that SyncClient is inconsistent with the server after refactor
Co-authored-by: Nxiangdong huang <sainthxd@gmail.com>

* set thrift and antlr as two independent module
Co-authored-by: Nxiangdong huang <sainthxd@gmail.com>

* Fix logic of creating MTree snapshot

* [IOTDB-503] Add checkTimeseriesExists for session
* [IOTDB-785] Disable anonymous access MQTT service

Co-authored-by: Nmychaow <941210239@qq.com>

* add a tsdb comaprison article

* support partition removal

* add compression keyword

* Add tracing on/off statement 

Add user guide and system design documents