Added HUD item box.
Created the item box graphic file under hud.xcf and hud.png. Loaded, rendered, and destroyed the box under HUD::loadBitmap(), HUD::destroyBitmap(), and HUD::renderBox(). Invoked Hud.renderBox() in thaed.cpp. The box is rendered on the top right side of the screen. Items will one day be displayed within the box.