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

src/gtk/gauge.cpp

@@ -32,7 +32,9 @@ bool wxGauge::Create( wxWindow *parent, wxWindowID id,  int range,
   
   PreCreation( parent, id, pos, size, style, name );
   
-  SetValidator( validator );
+#if wxUSE_VALIDATORS
+    SetValidator( validator );
+#endif
 
   m_rangeMax = range;
   m_gaugePos = 0;