tests for the last few issues (these test scripts should work with recent APIs, while the rest of the test suite needs an overhaul)

tests/test_children.py

@@ -0,0 +1,11 @@
+#!/usr/bin/env python3
+import sys
+import mcrfpy
+print("1")
+scene = mcrfpy.Scene("test")
+print("2")
+ui = scene.children
+print("3")
+print(f"children: {ui}")
+print("4")
+sys.exit(0)