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/providers/irc/AbstractIrcServer.cpp

@@ -327,10 +327,13 @@ void AbstractIrcServer::onReadConnected(IrcConnection *connection)
         if (replaceMessage)
         {
             chan->replaceMessage(snapshot[snapshot.size() - 1], reconnected);
-            continue;
+        }
+        else
+        {
+            chan->addMessage(connectedMsg);
         }
 
-        chan->addMessage(connectedMsg);
+        chan->connected.invoke();
     }
 
     this->falloffCounter_ = 1;