Add japanese localization (#522)

* 1

* update ja.json

* translate to side_panel

* translate to notifications

* translate to Discord RPC

* translate to sqlite_table_size

* update when_to_play

* translate to user

* translate to world actions

* translate to world info

* translate to avatar actions

* translate to group tags

* translate to world_import and several changes

* clear, 削除→消去

* 書き出す→エクスポート

* translate to friend_import

* finally

* add readme.jp

* translate to screenshots

* translate to launch parameter

* translate to repair db

* fix

* translate to how to build

* fix

* fix translation

* change screenshots (en to ja

* some fix

* update translation

* update translation

html/src/localization/localizedStrings.js

@@ -1,6 +1,9 @@
 import en from './strings/en.json' assert {type: 'JSON'};
 import elements_en from 'element-ui/lib/locale/lang/en';
-// import ja from './strings/ja.json' assert { type: 'JSON' };
+
+import ja from './strings/ja.json' assert { type: 'JSON' };
+import elements_ja from 'element-ui/lib/locale/lang/ja';
+
 import zh_TW from './strings/zh_TW.json' assert {type: 'JSON'};
 import elements_zh_TW from 'element-ui/lib/locale/lang/zh-TW';
 
@@ -14,10 +17,12 @@ const localized_en = {...en, ...elements_en};
 const localized_zh_TW = {...zh_TW, ...elements_zh_TW};
 const localized_zh_CN = {...zh_CN, ...elements_zh_CN};
 const localized_ko = {...ko, ...elements_ko};
+const localized_ja = {...ja, ...elements_ja};
 
 export {
     localized_en as en,
     localized_zh_TW as zh_TW,
     localized_ko as ko,
-    localized_zh_CN as zh_CN
+    localized_zh_CN as zh_CN,
+    localized_ja as ja_JP
 };