Abstract URL Escaping Process

The URL escaping process between model data, user presentation, and URL use needs to be abstracted.

In general, model data holds the "safest" URL encoding, like replacing spaces with underscores.
User presentation is the "prettiest" version, with spaces for underscores.
URL presentation depends on the reported client. Some browsers display spaces as spaces in their URL bars; others replace them with their percent-encoding. The URL presentation should use the browser information to display the "prettiest" URL possible.