Add NumActiveStatements() and test case

This reverts commit fbc7b773.

Fix inconsistency with Where and And on SQL builder.

Fix race condition when cached statements where closed while still in use

Make query error report errors on Query and QueryRow.

Drafting query logger and db config

Fix update nil column

Fix panic on SetLogger

Improve column guesses when inserting values

Bump up versions for testing.

Moving adapter benchmarks to db-bench