Use wx-prefixed macros throughout the repository.

Change {DECLARE,IMPLEMENT}_*CLASS and {DECLARE,BEGIN,END}_EVENT_TABLE
occurrences to use the wx-prefixed version of the macros.

samples/menu/menu.cpp

@@ -414,7 +414,7 @@ wxEND_EVENT_TABLE()
 // MyApp
 // ----------------------------------------------------------------------------
 
-IMPLEMENT_APP(MyApp)
+wxIMPLEMENT_APP(MyApp);
 
 // The `main program' equivalent, creating the windows and returning the
 // main frame