Add missing wxABI_VERSION checks and version script entries.

Newly overridden virtual methods must be taken in wxABI_VERSION checks as
otherwise any program using the class deriving from the one containing this
method would reference the method in the vtbl of that class and so become
ABI-incompatible with the earlier shared library versions.

Also add wxABI_VERSION guard around the entire wxSimplebookXmlHandler class
added in 3.0.2.

include/wx/gtk/dvrenderer.h

@@ -34,7 +34,9 @@ public:
     virtual void EnableEllipsize(wxEllipsizeMode mode = wxELLIPSIZE_MIDDLE);
     virtual wxEllipsizeMode GetEllipsizeMode() const;
 
+#if wxABI_VERSION >= 30003
     virtual bool FinishEditing();
+#endif
 
     // GTK-specific implementation
     // ---------------------------