New BAdI-Method to change the final mailtext (with signature and HTML coding)

The current BAdI-Method SET_MAILTEXT is called for the actual mailtext but does not contain the signature or html coding which was added via profile.

We need a new BAdI-Method (e.g. SET_MAILTEXT_FINAL) which is called when the final mailbody was created by the mailtext profile. The text, which could be changed by the method, should include HTML-Header, Text, Signature and HTML-Footer with all replacements of text-symbols done.