Fix DivEquals characters in menu

Move to Unicode rather than slash to avoid Unity turn it into a menu or spacer
Fix #852

Assets/Fungus/Scripts/Utils/VariableUtil.cs

@@ -65,8 +65,11 @@ namespace Fungus
                     break;
 
                 case SetOperator.Divide:
-                return "/=";
-                break;
+                    //https://answers.unity.com/questions/398495/can-genericmenu-item-content-display-.html
+                    // '/' in a menu means submenu and because it had no leading text, Unity thinks we want a spacer
+                    //  using unicode alternates for / fix the problem.
+                    return "\u200A\u2215\u200A=";
+                    break;
             }
 
             return string.Empty;