Add functions to clear ECS state

engine/core.scm

@@ -120,6 +120,12 @@
   (queue-del-entity id)
   id)
 
+;; Clear the entire world
+(define (clear-world)
+  (for-each
+   remove-entity
+   (hash-table-keys world)))
+
 ;; System record interface
 (export make-system system? system-name system-rendering
 	system-priority set-system-priority! system-criteria
@@ -235,6 +241,11 @@
   (queue-del-system name)
   name)
 
+(define (clear-systems)
+  (for-each
+   remove-system
+   (map system-name systems)))
+
 ;; Execute a single system
 ;; TODO: Implement
 (define (execute-system system)