Enemy bugs and level 21

Fixes:

- When Crate on an enemy, the enemy is still alive. Now the enemy will be gone
- At level 21, the Lime Crate can be pulled across # shaped Targets and solve the puzzle. Now level 21 is more difficult and moved to level 24
- When the enemy tries to push a Normal Crate or the Lime one into unintended Target, it will go underneath the Crate. Now has been fixed