GUI2/Dialogs: cleaned up a bunch of unnecessary forward declarations

src/gui/dialogs/game_version.hpp

@@ -30,7 +30,6 @@ class list_view;
 #else
 class listbox;
 #endif
-class stacked_widget;
 
 namespace dialogs
 {

src/gui/dialogs/help_browser.hpp

@@ -19,8 +19,6 @@
 #include <map>
 #include <list>
 
-class config;
-
 namespace help {
 	class section;
 }

src/gui/dialogs/preferences_dialog.hpp

@@ -61,10 +61,8 @@ namespace gui2
 
 class listbox;
 class menu_button;
-class styled_widget;
 class slider;
 class text_box;
-class toggle_button;
 
 namespace dialogs
 {

src/gui/dialogs/story_viewer.hpp

@@ -20,8 +20,6 @@
 #include "storyscreen/controller.hpp"
 #include "storyscreen/part.hpp"
 
-class CVideo;
-
 namespace gui2
 {
 namespace dialogs

src/gui/dialogs/unit_recall.hpp

@@ -23,7 +23,6 @@
 #include <vector>
 
 class team;
-class unit_type;
 
 namespace gui2
 {