Applications: Add Presenter

This version can already:
- load all of the defined file format except for the image type and the
  frame-specific stuff
- navigate frames and slides (though frames are mostly stubbed out)
- display text with various common settings
- displays text with various fitting and scaling methods
- scale and position objects correctly no matter the window size

Userland/Applications/Presenter/main.cpp

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2022, kleines Filmröllchen <filmroellchen@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "PresenterWidget.h"
+#include <LibCore/ArgsParser.h>
+#include <LibCore/System.h>
+#include <LibGUI/Application.h>
+#include <LibGUI/Icon.h>
+#include <LibGUI/Window.h>
+#include <LibMain/Main.h>
+
+ErrorOr<int> serenity_main(Main::Arguments arguments)
+{
+    // rpath is required to load .presenter files, unix, sendfd and recvfd are required to talk to ImageDecoder and WindowServer.
+    TRY(Core::System::pledge("stdio rpath unix sendfd recvfd"));
+
+    String file_to_load;
+    Core::ArgsParser argument_parser;
+    argument_parser.add_positional_argument(file_to_load, "Presentation to load", "file", Core::ArgsParser::Required::No);
+    argument_parser.parse(arguments);
+
+    auto app = TRY(GUI::Application::try_create(arguments));
+    auto window = TRY(GUI::Window::try_create());
+    window->set_title("Presenter");
+    window->set_icon(GUI::Icon::default_icon("app-display-settings"sv).bitmap_for_size(16));
+    auto main_widget = TRY(window->try_set_main_widget<PresenterWidget>());
+    TRY(main_widget->initialize_menubar());
+    window->show();
+
+    if (!file_to_load.is_empty())
+        main_widget->set_file(file_to_load);
+
+    return app->exec();
+}