Make various minor changes

src/base/search/searchpluginmanager.cpp

@@ -170,7 +170,7 @@ PluginInfo *SearchPluginManager::pluginInfo(const QString &name) const
 
 void SearchPluginManager::enablePlugin(const QString &name, const bool enabled)
 {
-    PluginInfo *plugin = m_plugins.value(name, 0);
+    PluginInfo *plugin = m_plugins.value(name, nullptr);
     if (plugin) {
         plugin->enabled = enabled;
         // Save to Hard disk

src/gui/addnewtorrentdialog.cpp

@@ -233,7 +233,7 @@ void AddNewTorrentDialog::saveState()
 
 void AddNewTorrentDialog::show(const QString &source, const BitTorrent::AddTorrentParams &inParams, QWidget *parent)
 {
-    AddNewTorrentDialog *dlg = new AddNewTorrentDialog(inParams, parent);
+    auto *dlg = new AddNewTorrentDialog(inParams, parent);
 
     if (Net::DownloadManager::hasSupportedScheme(source)) {
         // Launch downloader

src/gui/transferlistmodel.cpp

@@ -149,7 +149,7 @@ QVariant TransferListModel::headerData(int section, Qt::Orientation orientation,
             case TR_RATIO:
             case TR_PRIORITY:
             case TR_LAST_ACTIVITY:
-                return {Qt::AlignRight | Qt::AlignVCenter};
+                return QVariant(Qt::AlignRight | Qt::AlignVCenter);
             default:
                 return QAbstractListModel::headerData(section, orientation, role);
             }

src/webui/api/torrentscontroller.cpp

@@ -134,7 +134,7 @@ namespace
     QVariantList getStickyTrackers(const BitTorrent::TorrentHandle *const torrent)
     {
         uint seedsDHT = 0, seedsPeX = 0, seedsLSD = 0, leechesDHT = 0, leechesPeX = 0, leechesLSD = 0;
-        for (const BitTorrent::PeerInfo &peer : torrent->peers()) {
+        for (const BitTorrent::PeerInfo &peer : asConst(torrent->peers())) {
             if (peer.isConnecting()) continue;
 
             if (peer.isSeed()) {