Add a new feature

- Add support for specifying the songs of which only the `beyond` chart should be served #60

latest version/web/index.py

@@ -2,7 +2,7 @@ import os
 import time
 
 import server.arcscore
-from core.download import initialize_songfile
+from core.download import initialize_songfile, get_only_3_song_ids
 from core.rank import RankList
 from core.sql import Connect
 from flask import Blueprint, flash, redirect, render_template, request, url_for
@@ -288,6 +288,8 @@ def update_database():
 def update_song_hash():
     # 更新数据库内谱面文件hash值
     try:
+        get_only_3_song_ids.cache_clear()
+        get_only_3_song_ids()
         initialize_songfile()
         flash('数据刷新成功 Success refresh data.')
     except: