Move system initialization in systems.c, properly delete all entities when unloading map

game/components.h

@@ -6,6 +6,9 @@
 
 #include "game_tileset.h"
 
+// Needed, so we can clean up all game created entities
+extern ECS_TAG_DECLARE(GameEntity);
+
 typedef enum ResourceType {
     RES_IRON,
     RES_WOOD,
@@ -190,5 +193,11 @@ extern ECS_TAG_DECLARE(Attackable);
 
 void initComponentIDs(ecs_world_t *ecs);
 
+static ecs_entity_t entityCreate(ecs_world_t *ecs) {
+    ecs_entity_t entity = ecs_new_id(ecs);
+    ecs_add_id(ecs, entity, GameEntity);
+    return entity;
+}
+
 
 #endif //PIXELDEFENSE_COMPONENTS_H