fix [#35311] Planar Decimate / Limited Dissolve fails to merge some adjacent faces

optionally limit by face flipping, also added support to delimit by material and edge crease.

release/scripts/startup/bl_ui/properties_data_modifier.py

@@ -262,6 +262,9 @@ class DATA_PT_modifiers(ModifierButtonsPanel, Panel):
         else:  # decimate_type == 'DISSOLVE':
             layout.prop(md, "angle_limit")
             layout.prop(md, "use_dissolve_boundaries")
+            layout.label("Delimit:")
+            row = layout.row()
+            row.prop(md, "delimit")
 
         layout.label(text=iface_("Face Count: %d") % md.face_count, translate=False)