Fix a couple of inefficiencies in quickopen

1. We were refreshing the model twice!
2. Using set.insert() to check for duplicates is bad here as we
   keep growing in size..., use count() instead

kate/quickopen/katequickopen.cpp

@@ -274,7 +274,7 @@ KateQuickOpen::KateQuickOpen(KateMainWindow *mainWindow)
 
     setHidden(true);
 
-    slotListModeChanged(m_inputLine->listMode());
+    m_base_model->setListMode(m_inputLine->listMode());
 
     // fill stuff
     updateState();

kate/quickopen/katequickopenmodel.cpp

@@ -144,7 +144,7 @@ void KateQuickOpenModel::refresh(KateMainWindow *mainWindow)
 
     for (const auto &filePath : projectDocs) {
         // No duplicates
-        if (!openedDocUrls.insert(filePath).second) {
+        if (openedDocUrls.count(filePath) != 0) {
             continue;
         }