Fix model downloader crash on shutdown (#155)

* Fix `ModelDownloader` not being aware of child object deletions

* Delete `ModelDownloader` after it's done processing

Otherwise this is only deleted when OBS exits, effectively leaking
memory

src/model-utils/model-downloader-ui.cpp

@@ -66,8 +66,10 @@ void ModelDownloader::closeEvent(QCloseEvent *e)
 {
 	if (!this->mPrepareToClose)
 		e->ignore();
-	else
+	else {
 		QDialog::closeEvent(e);
+		deleteLater();
+	}
 }
 
 void ModelDownloader::close()

src/model-utils/model-downloader-ui.h

@@ -50,8 +50,8 @@ public slots:
 private:
 	QVBoxLayout *layout;
 	QProgressBar *progress_bar;
-	QThread *download_thread;
-	ModelDownloadWorker *download_worker;
+	QPointer<QThread> download_thread;
+	QPointer<ModelDownloadWorker> download_worker;
 	// Callback for when the download is finished
 	download_finished_callback_t download_finished_callback;
 	bool mPrepareToClose;