Adjust Creature sprite naming conventions

[nightm4re94]

Instead of creature-walk-right.png, use creature-move-right.png for automatic animationcontroller initialization.
Moving is a more generic name that applies also to creatures without legs.

Furthermore, determining the sprite states and directions by splitting spritesheet names at '-' characters is super prone to errors and doesn't allow you to deviate from the order at all. You can't, for example, call a sprite 'spaceship1-yellow-idle' because the 'yellow' part is then interpreted as sprite state. Use RegEx to determine sprite states and directions.