No longer add username to the completion model in privateMessageReceived

The username is added to the completion model with the
"addRecentChatter" method instead

Moved "NameOptions" stuff from base class Channel to TwitchChannel where
it belongs

Remove unused Channel::getUsernamesForCompletions method

src/channel.hpp

@@ -6,14 +6,10 @@
 #include "util/completionmodel.hpp"
 #include "util/concurrentmap.hpp"
 
-#include <QMap>
-#include <QMutex>
 #include <QString>
-#include <QVector>
 #include <boost/signals2.hpp>
 
 #include <memory>
-#include <set>
 
 namespace chatterino {
 namespace messages {
@@ -40,22 +36,11 @@ public:
     void addMessage(messages::MessagePtr message);
     void addMessagesAtStart(std::vector<messages::MessagePtr> &messages);
     void replaceMessage(messages::MessagePtr message, messages::MessagePtr replacement);
-    void addRecentChatter(const std::shared_ptr<messages::Message> &message);
-
-    struct NameOptions {
-        QString displayName;
-        QString localizedName;
-    };
-
-    std::vector<NameOptions> getUsernamesForCompletions();
+    virtual void addRecentChatter(const std::shared_ptr<messages::Message> &message);
 
     QString name;
     QStringList modList;
 
-    // Key = login name
-    std::map<QString, NameOptions> recentChatters;
-    std::mutex recentChattersMutex;
-
     virtual bool canSendMessage() const;
     virtual void sendMessage(const QString &message);
     virtual bool isMod() const