refactor: move main.py and core into new src folder

src/core/utils/general/shutdown.py

@@ -0,0 +1,9 @@
+import threading
+from core.network.libtorrent_misc import cleanup_session
+from core.utils.general.wrappers import run_thread
+
+shutdown_event = threading.Event()
+
+def closehelper():
+    run_thread(threading.Thread(target=cleanup_session))
+    shutdown_event.set()