CLI: Add interactive session mode command open

This change adds a GNU Readline-based interactive mode to keepassxc-cli. If GNU Readline is not available, commands are just read from stdin with no editing or auto-complete support.

DatabaseCommand is modified to add the path to the current database to the arguments passed to executeWithDatabase. In this way, instances of DatabaseCommand do not have to prompt to re-open the database after each invocation, and existing command implementations do not have to be changed to support interactive mode.

This change also introduces a new way of handling commands between interactive and batch modes.

* Fixes #3224.
* Ran make format

src/cli/Close.h

@@ -0,0 +1,32 @@
+/*
+ *  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_CLOSE_H
+#define KEEPASSXC_CLOSE_H
+
+#include <QStringList>
+
+#include "Command.h"
+
+class Close : public Command
+{
+public:
+    Close();
+    int execute(const QStringList& arguments) override;
+};
+
+#endif // KEEPASSXC_CLOSE_H