Bugfix list:

• IOTDB-1049 Fix Nullpointer exception and a delete bug in Last query
• IOTDB-1060 Support full deletion for delete statement without where clause
• IOTDB-1068 Fix Time series metadata cache bug
• IOTDB-1069 restrict the flushing memtable number to avoid OOM when mem_control is disabled
• IOTDB-1077 add insertOneDeviceRecords API in java session
• IOTDB-1087 fix compaction block flush: flush do not return until compaction finished
• IOTDB-1106 Delete timeseries statement will incorrectly delete other timeseries
• Github issue-2137 fix grafana value-time position bug
• Github issue-2169 GetObject returns String for all data types
• Github issue-2240 fix Sync failed: Socket is closed by peer
• Github issue-2387 The deleteData method exists in Session but not in SessionPool.
• add thrift_max_frame_size in iotdb-engine.properties
• Fix incorrect last result after deleting all data
• Fix compaction recover block restart: IoTDB cannot restart until last compaction recover task finished
• Fix compaction ignore modification file: delete does not work after compaction
• print more insert error message in client
• expose enablePartition parameter into iotdb-engines.properpties