Remove HTML P at end of generated HTML

[zipwiz]

Actually the generated HTML is finished by a single "<p>".

The technical reason for this is that the implemantation simply adds an opening "<p>" just in case there is still some text to come.

Syntactically spoken this is dangerous because there may follow other HTML running into problems with this "opened but not closed <p>". This finishing "<p>" should be removed therefore as soon as it is sure that the RTF source is completely consumed. This may be done at the very end of the transformation, just befor returning the result.

[zipwiz]

(I do not think that I will be able to work on this the next time because nearly all tests have to be adjusted.)