[SDL Text Display] New constructor for just label and bounding box.
[Entity] Fix typo.
[SDL Utility] Add FontSize type.
[SDL Button] Utilize font sizes.
[Game Manager] Game Manager should no longer load the sidebar. Pause button should be moved from side bar to main menu.
(+) [SDL Widget Container] Implement a Widget Container.

Widget Container inherits from both SdlWidget (does it need to?) and Config.

It requires a callback map and a config file.
[Sidebar Config] Remove Pause button. Add all the building and miracle buttons.
[Village Manager] Utilize the Widget Container. Add 'show' and 'hide' methods.
[Main] Add calls to village manager's 'show' and 'hide' methods.
[makefile] Add widget container to compilation.