[Battle] Add BattleCollector
[World] Implement equals, add tick
[World] Add hashCode method
[General] Fix trailing whitespaces
[General] Refatoring

Changed modifiers in classes, added setters
[World] Remove "final" from Object's methods
[Battle] BattleCollector extends Battle
[General] Refactoring

Remove getter of BattleCollector.worlds and make BattleCollector implement Iterable instead
Implement equals and hashCode for Battle, BattleCollector.
[BattleCollector] Removed testing equality by calling super method
[Simulation] Add Body class
[General] Refactoring
Cleanup
[BattleCollector] Custom iterator subclass added, not allowed to remove elements