revise progress persistent file format to reduce file size.
example: print out number of rows consumed

1. taos_consume block for evev
2. taos_fetch_block returns 0 in subscription

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.

Implemented higher level API to make it more modular
Using promises and callbacks
Argument binding is now available e.g query(select ? from ?).bind("*", "table")

Change the pom.xml for the JDBC demo project so that users can directly compile and package an executable jar with all the dependencies.