RETURNING support

[kibertoad]

underlying sqlite3 version does support RETURNING at last, but when we try to execute INSERT query with RETURNING clause in them, we get undefined response. Is there something that needs to be done to make that work?

[bpasero]

Our intent is not to create another distribution of this library but track the original library as closely as possible. In fact, #11 tracks upstreaming our changes and then we will delete this repository very likely.