query parser: add reading mode 'none'

ext/bg/data/options-schema.json

@@ -398,7 +398,7 @@
                                     },
                                     "readingMode": {
                                         "type": "string",
-                                        "enum": ["hiragana", "katakana", "romaji"],
+                                        "enum": ["hiragana", "katakana", "romaji", "none"],
                                         "default": "hiragana"
                                     }
                                 }

ext/bg/settings.html

@@ -457,6 +457,7 @@
                         <option value="hiragana">ひらがな</option>
                         <option value="katakana">カタカナ</option>
                         <option value="romaji">Romaji</option>
+                        <option value="none">Disabled</option>
                     </select>
                 </div>
             </div>

ext/mixed/js/japanese.js

@@ -80,6 +80,8 @@ function jpConvertReading(expressionFragment, readingFragment, readingMode) {
                 }
             }
             return readingFragment;
+        case 'none':
+            return null;
         default:
             return readingFragment;
     }