Allows SQLDialect to be inferred from the type SQLConnection.

[sadish-d]

Not sure if you're accepting pull requests, but here's a small edit.

import SQLite
import FunSQL: DBInterface, SQLConnection, reflect
DBInterface.connect(SQLConnection{SQLite.DB}) |> reflect  # `reflect` now works on the type `SQLConnection`.

If you think there is a better way to do this, please go ahead and ignore this pull request.