Library: exit search mode before creating a folder

Creating a folder in search mode selects it and makes the UI look
half-way between Normal and Searching navigation statuses.

An alternative fix is to disable addFolderAction in search mode. But
this is more difficult to implement and inconsistent with the other
always-enabled folder and reading list actions.

YACReaderLibrary/library_window.cpp

@@ -1572,6 +1572,8 @@ void LibraryWindow::enableNeededActions()
 
 void LibraryWindow::addFolderToCurrentIndex()
 {
+    exitSearchMode(); // Creating a folder in search mode is broken => exit it.
+
     QModelIndex currentIndex = getCurrentFolderIndex();
 
     bool ok;