Adding a basic combat system

include/systems/combat_manager.h

@@ -0,0 +1,21 @@
+/*
+** EPITECH PROJECT, 2020
+** my_rpg	
+** File description:
+** combat_manager.h
+*/
+
+
+#ifndef MY_RPG_COMBAT_MANAGER_H
+#define MY_RPG_COMBAT_MANAGER_H
+
+#include "system.h"
+
+struct combat_manager {
+    gc_system base;
+    gc_scene *game_scene;
+};
+
+extern const struct combat_manager combat_manager;
+
+#endif //MY_RPG_COMBAT_MANAGER_H