improve combat

[Bantolomeus]

• [ ] after an enemies hp bar is empty, it is defeated and the same monster appears with full health
• [ ] the players attack power is updated in real time
• [ ] optional: make the enemy and the player go up and down slightly
• [ ] if the optional task is not done put it into its own issue

[Bantolomeus]

• [x] show damage done as splash number over the enemy -> was moved into #33

[Bantolomeus]

• [x] after an enemies hp bar is empty, it is defeated and grants 1 attack power for the hero -> was moved into #40 for easier implementation and getting done faster.