[fix] fix various issues

- add edit mode switch before bm export to prevent potential error
- let the default value of ZBuffer in Virtools Material become True
- fix the issue that duplicated elements adder do not understand enable option.

ballance_blender_plugin/UTILS_virtools_prop.py

@@ -53,7 +53,7 @@ class BALLANCE_PG_virtools_material(bpy.types.PropertyGroup):
     z_buffer: bpy.props.BoolProperty(
         name="Z Buffer",
         description="ZFunc: VXCMP_LESSEQUAL.",
-        default=False,
+        default=True,
     )
 
     two_sided: bpy.props.BoolProperty(