Don't ask for saving changes when importing a SQL file

When importing a SQL file into a new database, we would create a
database file, import everything, then close the database and open it in
the GUI. While closing, however, the application asks you whether you
want to save the changes you made which can be confusing. This is solved
by creating an empty database, then closing it immediately without any
changes just to then open it in the GUI. Only then the import takes
place.

See comment in issue #1045.

src/MainWindow.cpp

@@ -1734,7 +1734,10 @@ void MainWindow::importDatabaseFromSQL()
             return;
         }
 
+        // Create the new file and open it in the browser
         db.create(newDbFile);
+        db.close();
+        fileOpen(newDbFile);
     }
 
     // Defer foreign keys. Just deferring them instead of disabling them should work fine because in the import we only expect CREATE and INSERT
@@ -1760,14 +1763,9 @@ void MainWindow::importDatabaseFromSQL()
     // Restore the former foreign key settings
     db.setPragma("defer_foreign_keys", foreignKeysOldSettings);
 
-    // Refresh window when importing into an existing DB or - when creating a new file - just open it correctly
-    if(newDbFile.size())
-    {
-        fileOpen(newDbFile);
-    } else {
-        db.updateSchema();
-        populateTable();
-    }
+    // Refresh views
+    db.updateSchema();
+    populateTable();
 }
 
 void MainWindow::openPreferences()