Updated the ClientApplication class to help support the new design, but
it's not finished because of that module's dependence on the various
scenes.
Updated the following scenes:
* CleanUp
* MainMenu
* OptionsMenu
The following source files (in client/scenes/) compile correctly:
* base_scene.cpp
* splash_screen.cpp
* clean_up.cpp
* main_menu.cpp
* options_menu.cpp
The folling source files (in client/scenes/) do not compile:
* in_world.cpp
* in_combat.cpp
* lobby_menu.cpp
Kayne Ruse