Add language selection with '/l(anguage)' command

WIP. Needs a way to save user's choice.

Usage: /l or /language

- Let user select the language he wants his message to translate to.
  When triggered, bot will send an inline keyboard message with a list
  of available langauges. For an example of an inline keyboard message,
  see https://core.telegram.org/bots#inline-keyboards-and-on-the-fly-updating.

@@ -137,3 +137,68 @@ bot.onText(/^\/(t|translate)($| ((.|\n)+))/, (msg, match) => {
     translate(received_msg, chatId);
   }
 });
+
+// /l(anguage)
+// Let user select the language he wants his message to translate to.
+// When triggered, bot will send an inline keyboard message with a list
+// of available langauges. For an example of an inline keyboard message,
+// see https://core.telegram.org/bots#inline-keyboards-and-on-the-fly-updating.
+bot.onText(/^\/(l|anguage)/, (msg, match) => {
+  const chatId = msg.chat.id;
+  const msgId = msg.message_id;
+
+  const inlineKeyboard = {
+    inline_keyboard: [
+      // Languages supported by papago language detection
+      // One array per line
+      [
+        { text: '한국어', callback_data: 'ko' },
+        { text: '영어', callback_data: 'en' },
+        { text: '일본어', callback_data: 'ja' }
+      ],
+      [
+        { text: '중국어 간체', callback_data: 'zh-cn' },
+        { text: '중국어 번체', callback_data: 'zh-tw' }
+      ],
+      [
+        { text: '힌디어', callback_data: 'hi' },
+        { text: '스페인어', callback_data: 'es' },
+        { text: '프랑스어', callback_data: 'fr' }
+      ],
+      [
+        { text: '독일어', callback_data: 'de' },
+        { text: '포루트갈어', callback_data: 'pt' },
+        { text: '베트남어', callback_data: 'vi' }
+      ],
+      [
+        { text: '인도네시아어', callback_data: 'id' },
+        { text: '페르시아어', callback_data: 'fa' }
+      ],
+      [
+        { text: '아랍어', callback_data: 'ar' },
+        { text: '미얀마어', callback_data: 'mm' },
+        { text: '태국어', callback_data: 'th' }
+      ],
+      [
+        { text: '러시아어', callback_data: 'ru' },
+        { text: '이탈리아어', callback_data: 'it' }
+      ],
+    ]
+  }
+  const options = {
+    reply_to_message_id: msgId,
+    reply_markup: inlineKeyboard
+  }
+
+  bot.sendMessage(chatId, '무슨 언어로 번역할까요? 선택은 기억됩니다.', options);
+});
+
+bot.on('callback_query', (query) => {
+  const data = query.data;
+
+  const options = {
+    text: 'From now on, your messages will be translated into ' + data
+  }
+
+  bot.answerCallbackQuery(query.id, options);
+});