First official release

Testing successfully on PG 9.5.

For now statistics are collected at each Executor hook (Start, Run, Finish, End) in order to get the sql_query appearing immediately; this has a significant impact on performance.

In further release I'll study the possibility to change this behaviour or see if the code can be optimized.

As it is my first C extension version number remain crappy (as it's a fork of pg_stat_statements)