Support for rendering rich media types

[SpencerPark]

To support rendering classes that you don't own in addition to a more OO approach there should be 2 ways to write render functions: via implementing an interface or registering a function (likely a lambda).

A render function takes an object of the type it can render and returns DisplayData.

A renderable object must serialize itself as DisplayData similar to toString() but richer instead.

Any objects that are not renderable are rendered as their string form.

[SpencerPark]

Published in 2.1.1-SNAPSHOT