Consume pop capacity + evade AI boiler plate

engine/breeze/ai/behaviour_tree.c

@@ -123,6 +123,17 @@ void bzBTDestroyRoot(BzObjectPool *nodePool, BzBTNode *node) {
 
     bzObjectPoolRelease(nodePool, node);
 }
+void bzBTSubTree(BzBTNode *tree, BzBTNode *parent) {
+    // Subtree must not have siblings
+    BZ_ASSERT(tree->prev == NULL && tree->next == NULL);
+    if (parent && parent->last) {
+        parent->last->next = tree;
+        parent->last = tree;
+    } else if (parent) {
+        parent->first = tree;
+        parent->last = tree;
+    }
+}
 
 BzBTNode *bzBTCompSelector(BzObjectPool *nodePool, BzBTNode *parent) {
     return bzBTNodeMake(nodePool, parent, BZ_BT_COMP_SELECTOR);

engine/breeze/ai/behaviour_tree.h

@@ -86,6 +86,8 @@ BzBTNode *bzBTMakeRoot(BzObjectPool *nodePool);
  */
 void bzBTDestroyRoot(BzObjectPool *nodePool, BzBTNode *node);
 
+void bzBTSubTree(BzBTNode *tree, BzBTNode *parent);
+
 /**
  * @brief Execute all children in turn until one fails.
  *