Remove println

Signed-off-by: Stephen Celis <stephen@stephencelis.com>
Support default expressions (like CURRENT_*)

Signed-off-by: Stephen Celis <stephen@stephencelis.com>
Add ALTER TABLE schema helpers

Supports RENAME TO:

    db.alter(table: users, rename: "people")

And ADD COLUMN:

    let name = Expression<String?>("name")
    db.alter(table: users, add: name)

Signed-off-by: Stephen Celis <stephen@stephencelis.com>