Add: 2 new states in GameState

Both facilitate waiting for an animation to finish.
Add: \ui\maingame\clueanimation.py

Clue opening animation implemented, but not yet used in actual program.
Small change: Text shadow offset in clue larger
Add: boxSize property in GameBoard

This property will be necessary to initialize OpenClueAnimation sprite.
Minor fix: categoryscroll import

categoryscroll.py was importing shadow_text from my utility library
rather than the game's local copy in \ui\util.py