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/generic/printps.cpp

@@ -30,6 +30,8 @@
 
 #include "wx/defs.h"
 
+#if wxUSE_PRINTING_ARCHITECTURE
+
 #ifndef WX_PRECOMP
     #include "wx/utils.h"
     #include "wx/dc.h"
@@ -345,3 +347,4 @@ void wxPostScriptPrintPreview::DetermineScaling()
     }
 }
 
+#endif