Update checking feature (#2648)

* Check on startup (toggleable setting) and manually
* Option to check for pre-releases (eg, 2.4.0-beta1)
* Only included if WITH_XC_NETWORKING is enabled

src/gui/UpdateCheckDialog.h

@@ -0,0 +1,50 @@
+/*
+ *  Copyright (C) 2019 KeePassXC Team <team@keepassxc.org>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 2 or (at your option)
+ *  version 3 of the License.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef KEEPASSXC_UPDATECHECKDIALOG_H
+#define KEEPASSXC_UPDATECHECKDIALOG_H
+
+#include <QUrl>
+#include <QDialog>
+#include <QScopedPointer>
+#include "gui/MessageBox.h"
+#include "config-keepassx.h"
+#include "core/Global.h"
+#include "updatecheck/UpdateChecker.h"
+
+namespace Ui
+{
+    class UpdateCheckDialog;
+}
+
+class UpdateCheckDialog : public QDialog
+{
+Q_OBJECT
+
+public:
+    explicit UpdateCheckDialog(QWidget* parent = nullptr);
+    ~UpdateCheckDialog() override;
+
+public slots:
+    void showUpdateCheckResponse(bool status, const QString& version);
+
+private:
+    QScopedPointer<Ui::UpdateCheckDialog> m_ui;
+};
+
+
+#endif //KEEPASSXC_UPDATECHECKDIALOG_H