Components which use PrimaryKeyEncoder should be changed to use ValueEncoder, and PrimaryKeyEncoder should be deprecated

While working on an application, I noticed that my objects were being serialized "weird" into a form by the loop component. I realized that I hadn't provided the primary key encoder, and once I did things worked as expected. That got me to thinking that it would be nice if the Loop component, and other components that rely on PrimaryKeyEncoders, could check to see if there is an encoder available for the value-type, if none is explicitly bound by the user. That way, module-authors could provide PrimaryKeyEncoders that makes things work "like magic".
For example, tapestry-hibernate could contribute PrimaryKeyEncoders for each entity type so that the objects are automatically, and properly, encoded into forms.