Battle scenes; confirmation popups

Implemented FanSelect - a new ViewComponent that allows quick selection
from a short list. Battle scene draws two characters facing each other
with a FanSelect component overlaid on both for intuitive functionality.
Renamed assets gen/images/sprites/character/player to assets
gen/images/sprites/character/human1. Organized Greg's newly committed
sprites into appropriate folders. Fixed incorrect argument being passed
to Scene#swappedIn. Pressing the Android menu key when InGameMenuScene
is open is now another way to close the menu. Implemented
ConfirmPopupScene and is used wherever appropriate.