Automatically load recent messages on reconnect (#3878)

* Add working reconnect recent messages

* Rename method to messagesUpdated

* Use audo declarations

* Add docs to new LimitedQueue methods

* Add more documentation, try atomic loading flag

* Update CHANGELOG.md

* Remove unused include

* Rename 'reconnected' signal to 'connected'

* Reserve before filtering on arbitrary update

* Extract recent messages fetching to own class

* Use std::atomic_flag instead of std::atomic_bool

* Add PostToThread include

* Add chatterino.recentmessages logging

* Remove unneeded parameters, lambda move capture

* Remove TwitchChannel::buildRecentMessages

* Add documentation, use more clear method name

* Reword changelog entry

I think it sounds better like this :)

* Rework how filling in missing messages is handled

This should hopefully prevent issues with filtered channels with old messages
that no longer exist in the underlying channel

* Check existing messages when looking for reply

* Clean up string distribution in file

* Try to improve documentation

* Use std::function for RecentMessagesApi

* Only trigger filledInMessages if we inserted

* Remove old unused lines

* Use make_shared<MessageLayout> instead of new MessageLayout

* Alphabetize QLogging categories

* Reorder CHANGELOG.md

src/common/Channel.hpp

@@ -57,8 +57,12 @@ public:
         messageAppended;
     pajlada::Signals::Signal<std::vector<MessagePtr> &> messagesAddedAtStart;
     pajlada::Signals::Signal<size_t, MessagePtr &> messageReplaced;
+    /// Invoked when some number of messages were filled in using time received
+    pajlada::Signals::Signal<const std::vector<MessagePtr> &> filledInMessages;
     pajlada::Signals::NoArgSignal destroyed;
     pajlada::Signals::NoArgSignal displayNameChanged;
+    /// Invoked when AbstractIrcServer::onReadConnected occurs
+    pajlada::Signals::NoArgSignal connected;
 
     Type getType() const;
     const QString &getName() const;
@@ -75,12 +79,17 @@ public:
     void addMessage(
         MessagePtr message,
         boost::optional<MessageFlags> overridingFlags = boost::none);
-    void addMessagesAtStart(std::vector<MessagePtr> &messages_);
+    void addMessagesAtStart(const std::vector<MessagePtr> &messages_);
+
+    /// Inserts the given messages in order by Message::serverReceivedTime.
+    void fillInMissingMessages(const std::vector<MessagePtr> &messages);
+
     void addOrReplaceTimeout(MessagePtr message);
     void disableAllMessages();
     void replaceMessage(MessagePtr message, MessagePtr replacement);
     void replaceMessage(size_t index, MessagePtr replacement);
     void deleteMessage(QString messageID);
+
     MessagePtr findMessage(QString messageID);
 
     bool hasMessages() const;