Improve column guesses when inserting values

Bump up versions for testing.

Moving adapter benchmarks to db-bench

Moving adapter benchmarks to https://github.com/upper/db-bench in order to make it easy to compare upper-db against other database abstractions

Add hasIsZero() interface to prevent  runtime errors

Add column schema guessing based on map/struct values

Play it nice with Go guru

Issue 237

fix upper/db#237

Fix concurrent map issue fixes #241

This reverts commit 0453b61e.

Improvements for SQLbuilder

Add batch insertion and test

fix typo

Simplify BatchInserter & Batch API

Fix sqlbuilder's One().