Recent updates in storage (#667)

* Fix error handling in Torrent.cpp, improve choosing peers for upload

* Various improvements in storage daemon

"get-pieces-info"
Store "added at"
Improve calculating up/down speed
Improve TL protocol for future compatibility
Remove empty directories on "--remove-files"
Better windows support
Debug logs in PeerActor
More restrictions on TorrentInfo
Bugfixes

* Global speed limits for download and upload

+bugfix

* Reset download/upload speed on changing settings or completion

* Exclude some system files in TorrentCreator

storage/SpeedLimiter.h

@@ -0,0 +1,52 @@
+/*
+    This file is part of TON Blockchain Library.
+
+    TON Blockchain Library is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation, either version 2 of the License, or
+    (at your option) any later version.
+
+    TON Blockchain Library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with TON Blockchain Library.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#pragma once
+#include "td/actor/actor.h"
+#include <queue>
+
+namespace ton {
+
+class SpeedLimiter : public td::actor::Actor {
+ public:
+  explicit SpeedLimiter(double max_speed);
+
+  void set_max_speed(double max_speed);  // Negative = unlimited
+  void enqueue(double size, td::Timestamp timeout, td::Promise<td::Unit> promise);
+
+  void alarm() override;
+
+ private:
+  double max_speed_ = -1.0;
+  td::Timestamp unlock_at_ = td::Timestamp::never();
+
+  struct Event {
+    td::Timestamp execute_at_;
+    double size_;
+    td::Timestamp timeout_;
+    td::Promise<td::Unit> promise_;
+  };
+  std::queue<Event> queue_;
+
+  void process_queue();
+};
+
+struct SpeedLimiters {
+  td::actor::ActorId<SpeedLimiter> download, upload;
+};
+
+}  // namespace ton