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/dataobj.h

@@ -345,11 +345,11 @@ public:
     virtual size_t GetLength() const { return m_html.Len() + 1; }
     virtual wxString GetHTML() const { return m_html; }
     virtual void SetHTML(const wxString& html) { m_html = html; }
-    
+
     virtual size_t GetDataSize() const wxOVERRIDE;
     virtual bool GetDataHere(void *buf) const wxOVERRIDE;
     virtual bool SetData(size_t len, const void *buf) wxOVERRIDE;
-    
+
     // Must provide overloads to avoid hiding them (and warnings about it)
     virtual size_t GetDataSize(const wxDataFormat&) const wxOVERRIDE
     {