Added ability for user to 'select' ClickableObjects.
Minor change of renaming AssetManager class caused refactor modification in several files.
New class NodeCollection allows storing Nodes for easy access later. So far storing FishNode and ClickableObjects (note, FishNode contains all fish, all fish are clickable, therefore ClickableObjects contains FishNode).
New classes GameInputManager and GameCamera provide same functionality as GameAssetManager (provide static/global access to the default InputManager and default Camera).
ActionHandler class split up into Pause and Click ActionHandler.