Remove all trailing spaces

No real changes, just clean up sources by removing trailing spaces from
all the non-generated files.

This should hopefully avoid future commits mixing significant changes
with insignificant whitespace ones.

include/wx/gtk/print.h

@@ -226,7 +226,7 @@ public:
 
     virtual void* GetCairoContext() const wxOVERRIDE;
     virtual void* GetHandle() const wxOVERRIDE;
-    
+
     bool CanDrawBitmap() const wxOVERRIDE { return true; }
     void Clear() wxOVERRIDE;
     void SetFont( const wxFont& font ) wxOVERRIDE;