Added a few #if wxUSE_XXX

Regrouped image format handlers
  Updated the rest accordingly
  Added changes.txt for wxGTK


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@2795 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/valgen.h

@@ -18,6 +18,8 @@
 
 #include "wx/validate.h"
 
+#if wxUSE_VALIDATORS
+
 class WXDLLEXPORT wxGenericValidator: public wxValidator
 {
 public:
@@ -55,4 +57,8 @@ protected:
   wxArrayInt* m_pArrayInt;
 };
 
-#endif    // _WX_VALGENH__
+#endif
+  // wxUSE_VALIDATORS
+
+#endif    
+  // _WX_VALGENH__