refactor: add explicit this-> where possible

I have knowingly skipped some files/portions of files where this would
create merge conflicts for other open PRs.

src/singletons/CrashHandler.cpp

@@ -132,7 +132,7 @@ using namespace std::string_literals;
 CrashHandler::CrashHandler(const Paths &paths_)
     : paths(paths_)
 {
-    auto optSettings = readRecoverySettings(paths);
+    auto optSettings = readRecoverySettings(this->paths);
     if (optSettings)
     {
         this->shouldRecover_ = *optSettings;

src/singletons/Settings.cpp

@@ -117,12 +117,12 @@ void Settings::mute(const QString &channelName)
 
 void Settings::unmute(const QString &channelName)
 {
-    for (std::vector<int>::size_type i = 0; i != mutedChannels.raw().size();
-         i++)
+    for (std::vector<int>::size_type i = 0;
+         i != this->mutedChannels.raw().size(); i++)
     {
-        if (mutedChannels.raw()[i].toLower() == channelName.toLower())
+        if (this->mutedChannels.raw()[i].toLower() == channelName.toLower())
         {
-            mutedChannels.removeAt(i);
+            this->mutedChannels.removeAt(i);
             i--;
         }
     }
@@ -132,7 +132,7 @@ bool Settings::toggleMutedChannel(const QString &channelName)
 {
     if (this->isMutedChannel(channelName))
     {
-        unmute(channelName);
+        this->unmute(channelName);
         return false;
     }
     else

src/singletons/Toasts.cpp

@@ -462,7 +462,7 @@ AvatarDownloader::AvatarDownloader(const QString &avatarURL,
         {
             this->file_.close();
         }
-        downloadComplete();
+        this->downloadComplete();
         this->deleteLater();
     });
 }

src/singletons/Updates.cpp

@@ -104,12 +104,12 @@ void Updates::deleteOldFiles()
 
 const QString &Updates::getCurrentVersion() const
 {
-    return currentVersion_;
+    return this->currentVersion_;
 }
 
 const QString &Updates::getOnlineVersion() const
 {
-    return onlineVersion_;
+    return this->onlineVersion_;
 }
 
 void Updates::installUpdates()

src/singletons/WindowManager.cpp

@@ -806,7 +806,7 @@ void WindowManager::closeAll()
     qCDebug(chatterinoWindowmanager) << "Shutting down (closing windows)";
     this->shuttingDown_ = true;
 
-    for (Window *window : windows_)
+    for (Window *window : this->windows_)
     {
         closeWindowsRecursive(window);
     }

src/singletons/helper/LoggingChannel.cpp

@@ -64,27 +64,28 @@ LoggingChannel::LoggingChannel(QString _channelName, QString _platform)
     {
         this->subDirectory = "Whispers";
     }
-    else if (channelName.startsWith("/mentions"))
+    else if (this->channelName.startsWith("/mentions"))
     {
         this->subDirectory = "Mentions";
     }
-    else if (channelName.startsWith("/live"))
+    else if (this->channelName.startsWith("/live"))
     {
         this->subDirectory = "Live";
     }
-    else if (channelName.startsWith("/automod"))
+    else if (this->channelName.startsWith("/automod"))
     {
         this->subDirectory = "AutoMod";
     }
     else
     {
         this->subDirectory =
-            QStringLiteral("Channels") + QDir::separator() + channelName;
+            QStringLiteral("Channels") + QDir::separator() + this->channelName;
     }
 
     // enforce capitalized platform names
-    this->subDirectory = platform[0].toUpper() + platform.mid(1).toLower() +
-                         QDir::separator() + this->subDirectory;
+    this->subDirectory = this->platform[0].toUpper() +
+                         this->platform.mid(1).toLower() + QDir::separator() +
+                         this->subDirectory;
 
     getSettings()->logPath.connect([this](const QString &logPath, auto) {
         this->baseDirectory = logPath.isEmpty()
@@ -196,8 +197,8 @@ void LoggingChannel::addMessage(const MessagePtr &message,
     }
 
     QString str;
-    if (channelName.startsWith("/mentions") ||
-        channelName.startsWith("/automod"))
+    if (this->channelName.startsWith("/mentions") ||
+        this->channelName.startsWith("/automod"))
     {
         str.append("#" + message->channelName + " ");
     }