Ajout des montagnes

src/main/java/app/SimulatorApplication.java

src/main/java/controller/Controller.java

src/main/java/model/Cloud.java

src/main/java/model/EmptyEntity.java

src/main/java/model/EmptySquare.java

src/main/java/model/Fire.java

src/main/java/model/FireFighter.java

src/main/java/model/FireFighterScenario.java

src/main/java/model/Mountain.java