LibGUI: Add GWindow::move_to().

Applications/Terminal/main.cpp

@@ -71,6 +71,8 @@ int main(int, char**)
     Terminal terminal(ptm_fd);
     window->set_main_widget(&terminal);
 
+    window->move_to(300, 300);
+
     GNotifier ptm_notifier(ptm_fd, GNotifier::Read);
     ptm_notifier.on_ready_to_read = [&terminal] (GNotifier& notifier) {
         byte buffer[BUFSIZ];

LibGUI/GWindow.h

@@ -32,6 +32,9 @@ public:
 
     Point position() const { return rect().location(); }
 
+    void move_to(int x, int y) { move_to({ x, y }); }
+    void move_to(const Point& point) { set_rect({ point, size() }); }
+
     virtual void event(GEvent&) override;
 
     bool is_visible() const;