Changed the default size of buttons and tabs from (0.0f, 0.0f) to
(50.0f, 20.0f). setSize and setText now takes an additional argument
resize. This allows you to change the size or text of a button or tab
without calling resizeFont() if needed.
Updated serveral includes and forward declarations related to trmb::Event
and sf::Transform.
Added a UI element class that acts as a single button. However, each click
toggles between two buttons. Allowing for "do" and "undo" functionality.