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*
IUnknown interface is used sometimes (e.g. in WinRT implementation of
wxNotificationMessage) alone, without other OLE routines, so it is
helpful to have its code in the separate file to avoid coupling with main
OLE code when only IUnknown implementation is required.