updated paqu-join to latest version that works with current sql parser

I finished the switch of PaQu to the newest version of the SQL parser. Further, I refactored many parts of the code and PaQu should now be ready to be hooked up to shard-query. 

I added the newest version to paqu-join.php.

The output of the query given in paqu-join.php now returns as expected.

Let me know how we will proceed with the continued implementation. Can you hook it up and I will see what queries in the PaQu test suite break and which are ok? And then we can identify any possible changes to shard-query that I did in PaQu and would be needed in the latest version of shard-query.