LibCore: Introduce a C_OBJECT macro.

This macro goes at the top of every CObject-derived class like so:

class SomeClass : public CObject {
    C_OBJECT(SomeClass)
public:
    ...

At the moment, all it does is create an override for the class_name() getter
but in the future this will be used to automatically insert member functions
into these classes.

Applications/IRCClient/IRCClient.h

@@ -15,9 +15,9 @@ class IRCWindowListModel;
 class CNotifier;
 
 class IRCClient final : public CObject {
+    C_OBJECT(IRCClient)
     friend class IRCChannel;
     friend class IRCQuery;
-
 public:
     IRCClient();
     virtual ~IRCClient() override;
@@ -87,8 +87,6 @@ public:
 
     void add_server_message(const String&);
 
-    const char* class_name() const override { return "IRCClient"; }
-
 private:
     struct Message {
         String prefix;

Applications/IRCClient/IRCWindow.h

@@ -10,6 +10,7 @@ class GTableView;
 class GTextEditor;
 
 class IRCWindow : public GWidget {
+    C_OBJECT(IRCWindow)
 public:
     enum Type {
         Server,
@@ -41,8 +42,6 @@ public:
     const IRCQuery& query() const { return *(const IRCQuery*)m_owner; }
 
 private:
-    const char* class_name() const override { return "IRCWindow"; }
-
     IRCClient& m_client;
     void* m_owner { nullptr };
     Type m_type;

Applications/PaintBrush/ColorDialog.h

@@ -3,10 +3,10 @@
 #include <LibGUI/GDialog.h>
 
 class ColorDialog final : public GDialog {
+    C_OBJECT(ColorDialog)
 public:
     explicit ColorDialog(Color, CObject* parent = nullptr);
     virtual ~ColorDialog() override;
-    virtual const char* class_name() const override { return "ColorDialog"; }
 
     Color color() const { return m_color; }
 

Applications/PaintBrush/PaintableWidget.h

@@ -4,14 +4,13 @@
 class Tool;
 
 class PaintableWidget final : public GWidget {
+    C_OBJECT(PaintableWidget)
 public:
     static PaintableWidget& the();
 
     explicit PaintableWidget(GWidget* parent);
     virtual ~PaintableWidget() override;
 
-    virtual const char* class_name() const override { return "PaintableWidget"; }
-
     Color primary_color() const { return m_primary_color; }
     Color secondary_color() const { return m_secondary_color; }
 

Applications/PaintBrush/PaletteWidget.h

@@ -5,12 +5,11 @@
 class PaintableWidget;
 
 class PaletteWidget final : public GFrame {
+    C_OBJECT(PaletteWidget)
 public:
     explicit PaletteWidget(PaintableWidget&, GWidget* parent);
     virtual ~PaletteWidget() override;
 
-    virtual const char* class_name() const override { return "PaletteWidget"; }
-
     void set_primary_color(Color);
     void set_secondary_color(Color);
 

Applications/PaintBrush/ToolboxWidget.h

@@ -3,11 +3,8 @@
 #include <LibGUI/GFrame.h>
 
 class ToolboxWidget final : public GFrame {
+    C_OBJECT(ToolboxWidget)
 public:
     explicit ToolboxWidget(GWidget* parent);
     virtual ~ToolboxWidget() override;
-
-    virtual const char* class_name() const override { return "ToolboxWidget"; }
-
-private:
 };

Applications/Taskbar/TaskbarWindow.h

@@ -3,14 +3,13 @@
 #include <LibGUI/GWindow.h>
 
 class TaskbarWindow final : public GWindow {
+    C_OBJECT(TaskbarWindow)
 public:
     TaskbarWindow();
     virtual ~TaskbarWindow() override;
 
     int taskbar_height() const { return 28; }
 
-    virtual const char* class_name() const override { return "TaskbarWindow"; }
-
 private:
     void on_screen_rect_change(const Rect&);
     GButton* create_button(const WindowIdentifier&);

Applications/Terminal/Terminal.h

@@ -56,6 +56,7 @@ private:
 };
 
 class Terminal final : public GFrame {
+    C_OBJECT(Terminal)
 public:
     explicit Terminal(int ptm_fd, RefPtr<CConfigFile> config);
     virtual ~Terminal() override;
@@ -92,7 +93,6 @@ private:
     virtual void mousedown_event(GMouseEvent&) override;
     virtual void mousemove_event(GMouseEvent&) override;
     virtual void mouseup_event(GMouseEvent&) override;
-    virtual const char* class_name() const override { return "Terminal"; }
 
     void scroll_up();
     void scroll_down();