turning a lot of includes into forward declares

src/widgets/helper/TitlebarButton.hpp

@@ -4,29 +4,29 @@
 
 namespace chatterino {
 
+enum class TitleBarButtonStyle {
+    None = 0,
+    Minimize = 1,
+    Maximize = 2,
+    Unmaximize = 4,
+    Close = 8,
+    User = 16,
+    Settings = 32
+};
+
 class TitleBarButton : public Button
 {
 public:
-    enum Style {
-        None = 0,
-        Minimize = 1,
-        Maximize = 2,
-        Unmaximize = 4,
-        Close = 8,
-        User = 16,
-        Settings = 32
-    };
-
     TitleBarButton();
 
-    Style getButtonStyle() const;
-    void setButtonStyle(Style style_);
+    TitleBarButtonStyle getButtonStyle() const;
+    void setButtonStyle(TitleBarButtonStyle style_);
 
 protected:
     void paintEvent(QPaintEvent *) override;
 
 private:
-    Style style_;
+    TitleBarButtonStyle style_;
 };
 
 }  // namespace chatterino