Adds transparent time travel to an Ecto.Repo.
Use it immediately after use Ecto.Repo:
use Ecto.Repo, otp_app: :my_app, adapter: Ecto.Adapters.Postgres
use SysTime.RepoThe generated prepare_query/3 remains overridable. A repository with its own
hook can call super/3 to retain SysTime's source rewrite.