Libraries: Create top level directory for libraries.

Things were getting a little crowded in the project root, so this patch
moves the Lib*/ directories into Libraries/.

Libraries/LibGUI/GToolBar.h

@@ -0,0 +1,34 @@
+#pragma once
+
+#include <LibGUI/GWidget.h>
+
+class GAction;
+
+class GToolBar : public GWidget {
+public:
+    explicit GToolBar(GWidget* parent);
+    virtual ~GToolBar() override;
+
+    void add_action(NonnullRefPtr<GAction>&&);
+    void add_separator();
+
+    bool has_frame() const { return m_has_frame; }
+    void set_has_frame(bool has_frame) { m_has_frame = has_frame; }
+
+    virtual const char* class_name() const override { return "GToolBar"; }
+
+private:
+    virtual void paint_event(GPaintEvent&) override;
+
+    struct Item {
+        enum Type {
+            Invalid,
+            Separator,
+            Action
+        };
+        Type type { Invalid };
+        RefPtr<GAction> action;
+    };
+    Vector<OwnPtr<Item>> m_items;
+    bool m_has_frame { true };
+};