Fix spelling in comments and documentation using codespell

Apply the utility from https://github.com/codespell-project/codespell/
to fix spelling issues in the headers under both include and interface
directories and add a file with a couple of exceptions.

The exact command line used was:

    $ codespell -w -I misc/scripts/codespell.ignore -i 3 in*

include/wx/frame.h

@@ -18,7 +18,7 @@
 #include "wx/toplevel.h"      // the base class
 #include "wx/statusbr.h"
 
-// the default names for various classs
+// the default names for various classes
 extern WXDLLIMPEXP_DATA_CORE(const char) wxStatusLineNameStr[];
 extern WXDLLIMPEXP_DATA_CORE(const char) wxToolBarNameStr[];