* Add support for async query. Only insert result is parsed.

* Add support for connection pool.

* Add one case for lua connector in smoke test case list.

* Build dymanic library for lua connector before smoke test.

* Set value for std with c99 to avoid compile error on CentOS7.

* Get parameter from stack by same sequence.

* Add performance test.

Connector is implemented by lua51 but luajit and ffi are not included. Connection pool is not implemented yet. It is a raw demonstration at present and not verified on production environment.

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.

Malloc memory to store Lua state and callback function from Lua. Connector can support multiple connection by this way.
Memory will be freed when connection isn't established successfully or connection is closed by lua call. Stream content
in Lua is not the same one with stream content in connector.

A loop in test code do the job for continuous query. record is inserted between query actions.

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.