feat: support blender 4.2 extension

extension/__init__.py

@@ -0,0 +1,22 @@
+import bpy
+
+from . import auto_load
+from . import menus
+
+
+auto_load.init()
+
+
+def register():
+    auto_load.register()
+    menus.add()
+    bpy.types.Scene.bioxel_layer_dir = bpy.props.StringProperty(
+        name="Bioxel Layers Directory",
+        subtype='DIR_PATH',
+        default="//"
+    )
+
+
+def unregister():
+    menus.remove()
+    auto_load.unregister()