DOC:
[TD- ] Updates for Java Connector markdown files
[TD- ] Changed the description of quotation marks in password change
[TD- ] Fix timestamp precision description.
[TD- ] Improve building steps with specific linux distributions
[TD- ] Improve the readme document with building steps
[TD- ] Modify wallevel description in section 2 of Master/Slave vnode writing process
[TD- ] Update TAOS SQL-ch.md
[TD- ] Update faq-ch.md
[TD- ] Fix some typo and expired content in documents.
[TD- ] Add entrance for Lua connector introduction.

FIX BUGS:
[TD-804] refresh meta data if SQL cannot be parsed
[TD-225] fix last query bug and add some function definitions. Add test cases, Fix compiler error.
[TD-934] fix invalid SQL
[TD-1248 TD-1044 TD-1247] fix crash in tcache.c
[TD-1227] add test case
[TD-1302] Interval query ignores the loading of data block, resulting in crash
[TD-1278] fix bug: If the tag is too long, no error will be reported
[TD-1250] Support the join of nchar
[TD-1099] natual interval in stream and bug fix, natual month/year processing
[TD-621] Looking for the hidden trouble of memory allocation failure in query process
[TD-1173] Invalid account permission setting
[TD-1247] crash while release hash obj
[TD-1230] last_ Row supports time range filtering
[TD-1257] Starting a non master node first may cause the cluster to be out of sync
[TD-1090] compile error in windows
[TD- ] Fixed a problem with crash_gen tool, so that it releases DB connections properly
[TD- ] Update query api for Lua connector.
[TD- ] All connectors should be updated since taos_query has been modified for thread safety. Only query api is updated, callback in stream is not yet.
[TD- ] Fixed a major problem in crash_gen tool, now it properly releases DB connections
[TD- ] daemon works with strict mode now.
[TD- ] add docker repo link
[TD- ] fix var/log/taos permission issue.
[TD- ] add historyfile plug to access .taos_history file.
[TD- ] Update query api for Lua connector.
[TD- ] add more check on data compress and decompress
[TD- ] updates for Java Connector

NEW FEATURES:
[TD-1256] Add description in faq for integrating network connectivity test into Taos program

ENHANCEMENTS:
[TD-1206] Optimizing the query performance of percentile with a new temporary file storage structure
[TD-1204] Improve the performance of restful interface
[TD- ] add natural interval support, now if query with: select count(*) from meters interval(1n);
the actual interval is natural month instead of 30 days. here n is for natural month, and y is for natural year.
[TD- ] last_row function supports time range filtering，and this time filter works as expected.