Improve order by/selection logic for database layer.

This was extracted from the postponed !311 (closed).

The order by stuff previously only allowed specifying a particular field. We should also be able to sort based on arbitrary expressions, and such expressions will require the ability to bind arguments using the "?" syntax. This change provides a Java abstraction for the order by, and improves the handling of selection arguments that need to bind to "?" so that both the selection (i.e. WHERE clause) and the ORDER BY clause can provide arguments as required.