Complete refactor of project file structure

Fix incorrect handing of default node parameters in SSD subscription.
Fix unable to parse some Clash rule-providers (#289).
Fix not filtering inline comments in some Surge rulesets. (#285)
Add Cron task options.
Add clean context option for persisting a JS context across the whole request.
Replace JS engine with QuickJS.

src/handler/multithread.h

@@ -0,0 +1,27 @@
+#ifndef MULTITHREAD_H_INCLUDED
+#define MULTITHREAD_H_INCLUDED
+
+#include <mutex>
+#include <future>
+
+#include <yaml-cpp/yaml.h>
+
+#include "../utils/ini_reader/ini_reader.h"
+#include "../utils/string.h"
+
+using guarded_mutex = std::lock_guard<std::mutex>;
+
+string_array safe_get_emojis();
+string_array safe_get_renames();
+string_array safe_get_streams();
+string_array safe_get_times();
+YAML::Node safe_get_clash_base();
+INIReader safe_get_mellow_base();
+void safe_set_emojis(string_array &data);
+void safe_set_renames(string_array &data);
+void safe_set_streams(string_array &data);
+void safe_set_times(string_array &data);
+std::shared_future<std::string> fetchFileAsync(const std::string &path, const std::string &proxy, int cache_ttl, bool async = false);
+std::string fetchFile(const std::string &path, const std::string &proxy, int cache_ttl);
+
+#endif // MULTITHREAD_H_INCLUDED