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.