The core implementation of the DataTable and DataTable.Base Widgets.

Use this class extension with Widget or another Base-based superclass to create the basic DataTable API and composing class structure.

Notable about this architecture is that rendering and UI event management for the header, body, and footer of the table are deferred to configurable classes in the headerView, bodyView, and footerView attributes. In this extension they have no default values, requiring implementers to supply their own classes to render the table content.