Remove wx/{treebook,textbuf,srchctrl,socket}.h from *.h

src/prefs/KeyConfigPrefs.h

@@ -16,7 +16,6 @@ class CommandManager;
 class ShuttleGui;
 
 #include <wx/defs.h>
-#include <wx/srchctrl.h>
 #include <wx/timer.h>
 
 #include "../widgets/KeyView.h"

src/prefs/PrefsDialog.h

@@ -13,10 +13,11 @@
 #define __AUDACITY_PREFS_DIALOG__
 
 #include <vector>
-#include <wx/treebook.h>
 #include "../widgets/wxPanelWrapper.h"
 #include "../Internat.h"
 
+class wxTreebook;
+class wxTreeEvent;
 class PrefsPanel;
 class PrefsPanelFactory;
 class ShuttleGui;