Currently CustomDatatype has a render(String referenceString, String view) method. Datatypes are at the API level and really don't need to know about views.
The one thing we really do want to be able to do is to rapidly render a summary view of a custom value.
- remove the render(String, String) method from the CustomDatatype interface
- remove it from all CustomDatatype implementations.
- add a toSummary method, something like what is described below
- implement toSummary in all CustomDatatype implementations.