[SDL Button, Widget] Move bounding box initialization from inherited class to parent class.
[SDL Widget] Implement text widget.
[SDL Manager] Implement text widget support.
[SDL Manager] Remove my_dot from test method.
[SDL Manager] Remove commented code from my_dot from test method.
[SDL Manager] Migrate test loop into update method.

Will need to implement event subscriptions so they don't have to be loaded into the switch statement.
[SDL Manager] Rename base widget class to SdlWidgetBase. Rename text widget class to more generic SdlWidget.